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The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells’ potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry’s concern for the purity of the wells’ oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil contaminated water.The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth’s surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well’s location was based on a poor understanding of the area’s subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area’s groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.Which one of the following most accurately states the main point of the passage?a)Although now recognized as undesirable, occasional groundwater contamination by oil and unpotable saline water is considered to be inevitable wherever drilling for oil occurs.b)Widespread coastal contamination caused by oil well drilling in North America has prompted international concern over oil exploration.c)Hindsight has been the only reliable means available to regulation writers responsible for devising adequate safeguard regulations to prevent environmental contamination associated with oil well drilling.d)The risk of environmental contamination associated with oil well drilling continues to exist because safeguard regulations are often based on hindsight and less-than-sufficient scientific information.e)Groundwater contamination associated with oil well drilling is due in part to regulations designed to protect the oil from contamination by groundwater and not the groundwater from contamination by oil.Correct answer is option 'D'. Can you explain this answer? for GMAT 2024 is part of GMAT preparation. The Question and answers have been prepared according to the GMAT exam syllabus. Information about The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells’ potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry’s concern for the purity of the wells’ oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil contaminated water.The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth’s surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well’s location was based on a poor understanding of the area’s subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area’s groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.Which one of the following most accurately states the main point of the passage?a)Although now recognized as undesirable, occasional groundwater contamination by oil and unpotable saline water is considered to be inevitable wherever drilling for oil occurs.b)Widespread coastal contamination caused by oil well drilling in North America has prompted international concern over oil exploration.c)Hindsight has been the only reliable means available to regulation writers responsible for devising adequate safeguard regulations to prevent environmental contamination associated with oil well drilling.d)The risk of environmental contamination associated with oil well drilling continues to exist because safeguard regulations are often based on hindsight and less-than-sufficient scientific information.e)Groundwater contamination associated with oil well drilling is due in part to regulations designed to protect the oil from contamination by groundwater and not the groundwater from contamination by oil.Correct answer is option 'D'. Can you explain this answer? covers all topics & solutions for GMAT 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells’ potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry’s concern for the purity of the wells’ oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil contaminated water.The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth’s surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well’s location was based on a poor understanding of the area’s subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area’s groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.Which one of the following most accurately states the main point of the passage?a)Although now recognized as undesirable, occasional groundwater contamination by oil and unpotable saline water is considered to be inevitable wherever drilling for oil occurs.b)Widespread coastal contamination caused by oil well drilling in North America has prompted international concern over oil exploration.c)Hindsight has been the only reliable means available to regulation writers responsible for devising adequate safeguard regulations to prevent environmental contamination associated with oil well drilling.d)The risk of environmental contamination associated with oil well drilling continues to exist because safeguard regulations are often based on hindsight and less-than-sufficient scientific information.e)Groundwater contamination associated with oil well drilling is due in part to regulations designed to protect the oil from contamination by groundwater and not the groundwater from contamination by oil.Correct answer is option 'D'. Can you explain this answer?.

Solutions for The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells’ potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry’s concern for the purity of the wells’ oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil contaminated water.The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth’s surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well’s location was based on a poor understanding of the area’s subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area’s groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.Which one of the following most accurately states the main point of the passage?a)Although now recognized as undesirable, occasional groundwater contamination by oil and unpotable saline water is considered to be inevitable wherever drilling for oil occurs.b)Widespread coastal contamination caused by oil well drilling in North America has prompted international concern over oil exploration.c)Hindsight has been the only reliable means available to regulation writers responsible for devising adequate safeguard regulations to prevent environmental contamination associated with oil well drilling.d)The risk of environmental contamination associated with oil well drilling continues to exist because safeguard regulations are often based on hindsight and less-than-sufficient scientific information.e)Groundwater contamination associated with oil well drilling is due in part to regulations designed to protect the oil from contamination by groundwater and not the groundwater from contamination by oil.Correct answer is option 'D'. Can you explain this answer? in English & in Hindi are available as part of our courses for GMAT. Download more important topics, notes, lectures and mock test series for GMAT Exam by signing up for free.

Here you can find the meaning of The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells’ potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry’s concern for the purity of the wells’ oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil contaminated water.The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth’s surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well’s location was based on a poor understanding of the area’s subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area’s groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.Which one of the following most accurately states the main point of the passage?a)Although now recognized as undesirable, occasional groundwater contamination by oil and unpotable saline water is considered to be inevitable wherever drilling for oil occurs.b)Widespread coastal contamination caused by oil well drilling in North America has prompted international concern over oil exploration.c)Hindsight has been the only reliable means available to regulation writers responsible for devising adequate safeguard regulations to prevent environmental contamination associated with oil well drilling.d)The risk of environmental contamination associated with oil well drilling continues to exist because safeguard regulations are often based on hindsight and less-than-sufficient scientific information.e)Groundwater contamination associated with oil well drilling is due in part to regulations designed to protect the oil from contamination by groundwater and not the groundwater from contamination by oil.Correct answer is option 'D'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells’ potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry’s concern for the purity of the wells’ oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil contaminated water.The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth’s surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well’s location was based on a poor understanding of the area’s subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area’s groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.Which one of the following most accurately states the main point of the passage?a)Although now recognized as undesirable, occasional groundwater contamination by oil and unpotable saline water is considered to be inevitable wherever drilling for oil occurs.b)Widespread coastal contamination caused by oil well drilling in North America has prompted international concern over oil exploration.c)Hindsight has been the only reliable means available to regulation writers responsible for devising adequate safeguard regulations to prevent environmental contamination associated with oil well drilling.d)The risk of environmental contamination associated with oil well drilling continues to exist because safeguard regulations are often based on hindsight and less-than-sufficient scientific information.e)Groundwater contamination associated with oil well drilling is due in part to regulations designed to protect the oil from contamination by groundwater and not the groundwater from contamination by oil.Correct answer is option 'D'. Can you explain this answer?, a detailed solution for The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells’ potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry’s concern for the purity of the wells’ oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil contaminated water.The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth’s surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well’s location was based on a poor understanding of the area’s subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area’s groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.Which one of the following most accurately states the main point of the passage?a)Although now recognized as undesirable, occasional groundwater contamination by oil and unpotable saline water is considered to be inevitable wherever drilling for oil occurs.b)Widespread coastal contamination caused by oil well drilling in North America has prompted international concern over oil exploration.c)Hindsight has been the only reliable means available to regulation writers responsible for devising adequate safeguard regulations to prevent environmental contamination associated with oil well drilling.d)The risk of environmental contamination associated with oil well drilling continues to exist because safeguard regulations are often based on hindsight and less-than-sufficient scientific information.e)Groundwater contamination associated with oil well drilling is due in part to regulations designed to protect the oil from contamination by groundwater and not the groundwater from contamination by oil.Correct answer is option 'D'. Can you explain this answer? has been provided alongside types of The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells’ potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry’s concern for the purity of the wells’ oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil contaminated water.The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth’s surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well’s location was based on a poor understanding of the area’s subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area’s groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.Which one of the following most accurately states the main point of the passage?a)Although now recognized as undesirable, occasional groundwater contamination by oil and unpotable saline water is considered to be inevitable wherever drilling for oil occurs.b)Widespread coastal contamination caused by oil well drilling in North America has prompted international concern over oil exploration.c)Hindsight has been the only reliable means available to regulation writers responsible for devising adequate safeguard regulations to prevent environmental contamination associated with oil well drilling.d)The risk of environmental contamination associated with oil well drilling continues to exist because safeguard regulations are often based on hindsight and less-than-sufficient scientific information.e)Groundwater contamination associated with oil well drilling is due in part to regulations designed to protect the oil from contamination by groundwater and not the groundwater from contamination by oil.Correct answer is option 'D'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice The accumulation of scientific knowledge regarding the environmental impact of oil well drilling in North America has tended to lag behind the actual drilling of oil wells. Most attempts to regulate the industry have relied on hindsight: the need for regulation becomes apparent only after undesirable events occur. The problems associated with oil wells’ potential contamination of groundwater—fresh water within the earth that supplies wells and springs—provide a case in point.When commercial drilling for oil began in North America in the mid-nineteenth century, regulations reflected the industry’s concern for the purity of the wells’ oil. In 1893, for example, regulations were enacted specifying well construction requirements to protect oil and gas reserves from contamination by fresh water. Thousands of wells were drilled in such a way as to protect the oil, but no thought was given to the possibility that the groundwater itself might need protection until many drinking-water wells near the oil well sites began to produce unpotable, oil contaminated water.The reason for this contamination was that groundwater is usually found in porous and permeable geologic formations near the earth’s surface, whereas petroleum and unpotable saline water reservoirs are generally found in similar formations but at greater depths. Drilling a well creates a conduit connecting all the formations that it has penetrated. Consequently, without appropriate safeguards, wells that penetrate both groundwater and oil or saline water formations inevitably contaminate the groundwater. Initial attempts to prevent this contamination consisted of sealing off the groundwater formations with some form of protective barrier to prevent the oil flowing up the well from entering or mixing with the natural groundwater reservoir. This method, which is still in use today, initially involved using hollow trees to seal off the groundwater formations; now, however, large metal pipe casings, set in place with cement, are used.Regulations currently govern the kinds of casing and cement that can be used in these practices; however, the hazards of insufficient knowledge persist. For example, the long-term stability of this way of protecting groundwater is unknown. The protective barrier may fail due to corrosion of the casing by certain fluids flowing up the well, or because of dissolution of the cement by these fluids. The effects of groundwater bacteria, traffic vibrations, and changing groundwater chemistry are likewise unassessed. Further, there is no guarantee that wells drilled in compliance with existing regulations will not expose a need for research in additional areas: on the west coast of North America, a major disaster recently occurred because a well’s location was based on a poor understanding of the area’s subsurface geology. Because the well was drilled in a channel accessing the ocean, not only was the area’s groundwater completely contaminated, but widespread coastal contamination also occurred, prompting international concern over oil exploration and initiating further attempts to refine regulations.Which one of the following most accurately states the main point of the passage?a)Although now recognized as undesirable, occasional groundwater contamination by oil and unpotable saline water is considered to be inevitable wherever drilling for oil occurs.b)Widespread coastal contamination caused by oil well drilling in North America has prompted international concern over oil exploration.c)Hindsight has been the only reliable means available to regulation writers responsible for devising adequate safeguard regulations to prevent environmental contamination associated with oil well drilling.d)The risk of environmental contamination associated with oil well drilling continues to exist because safeguard regulations are often based on hindsight and less-than-sufficient scientific information.e)Groundwater contamination associated with oil well drilling is due in part to regulations designed to protect the oil from contamination by groundwater and not the groundwater from contamination by oil.Correct answer is option 'D'. Can you explain this answer? tests, examples and also practice GMAT tests.