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he level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.
Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?
  • a)
    The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.
  • b)
    Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.
  • c)
    Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.
  • d)
    Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.
  • e)
    Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.
Correct answer is option 'B'. Can you explain this answer?
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Most Upvoted Answer
he level of lead contamination in United States rivers declined betwee...
Seems to be a bit of back and forth on this, so I thought I'd try to take it on using the (dreaded) process. I know, I know. Nothing's less fun then taking notes...but let's do it anyway:
Conclusion: Major cause of decline in LC was decline in lead gas [It's pretty common to find the conclusion in the question stem...so always be on the lookout]
Premises: Decline between 75 and 85. Feds said industrial discharge down in 1975. 75% drop in lead gasoline between 75 and 85.
Assumption: Industrial discharge didn't do it. [Basically, we're looking for something to downplay the importance of the legislation.]
(A) The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.
Problem: This would possibly weaken. We wouldn't want to see sharp declines, because it sounds like the drop was gradual (as lead gas was phased out).
(B) Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.
Answer: Well, if the industrial decline occurred before 1976, that means that the effect of the legislation was almost immediate. But if the contamination dropped mostly between 80 and 85, that could only be because of the rise of unleaded gas.
(C) Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.
Problem: This weakens a lot. This sounds like the legislation had a big effect, and then nothing happened for the rest of the time. We wanted gas to slowly make things better, but they're actually getting worse!
(D) Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.
Problem: This doesn't connect to either industry or gas, so it's irrelevant.
(E) Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.
Problem: Alright. Here's the toughie. The problem is that this doesn't actually add any information that we didn't have in the passage itself. Looks like it does, doesn't it? But think about it. We already knew the use of leaded gasoline declined 75 percent between 75 and 85 (that part is LITERALLY in the passage word for word). Then we're just told that most of it happened at the end. So what? That doesn't tell us anything about the contamination itself. What we really wanted was to WEAKEN the influence of the legislation, which B does.
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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?

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.The passage states which one of the following about underground oil reservoirs?

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.The author’s attitude regarding oil well drilling regulations can most accurately be described as

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he level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?a)The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.b)Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.c)Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.d)Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.e)Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.Correct answer is option 'B'. Can you explain this answer?
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he level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?a)The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.b)Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.c)Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.d)Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.e)Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.Correct answer is option 'B'. 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 he level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?a)The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.b)Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.c)Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.d)Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.e)Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.Correct answer is option 'B'. Can you explain this answer? covers all topics & solutions for GMAT 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for he level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?a)The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.b)Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.c)Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.d)Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.e)Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.Correct answer is option 'B'. Can you explain this answer?.
Solutions for he level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?a)The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.b)Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.c)Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.d)Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.e)Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.Correct answer is option 'B'. 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 he level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?a)The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.b)Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.c)Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.d)Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.e)Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.Correct answer is option 'B'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of he level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?a)The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.b)Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.c)Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.d)Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.e)Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.Correct answer is option 'B'. Can you explain this answer?, a detailed solution for he level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?a)The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.b)Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.c)Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.d)Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.e)Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.Correct answer is option 'B'. Can you explain this answer? has been provided alongside types of he level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?a)The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.b)Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.c)Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.d)Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.e)Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.Correct answer is option 'B'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice he level of lead contamination in United States rivers declined between 1975 and 1985. Federal regulations requiring a drop in industrial discharges of lead went into effect in 1975, but the major cause of the decline was a 75 percent drop in the use of leaded gasoline between 1975 and 1985.Which of the following, if true, best supports the claim that the major cause of the decline in the level of lead contamination in United States rives was the decline in the use of leaded gasoline?a)The level of lead contamination in United States rivers fell sharply in both 1975 and 1983.b)Most of the decline in industrial discharges of lead occurred before 1976, but the largest decline in the level of river contamination occurred between 1980 and 1985.c)Levels of lead contamination in rivers fell sharply in 1975-1976 and rose very slightly over the next nine years.d)Levels of lead contamination rose in those rivers where there was reduced river flow due to drought.e)Although the use of leaded gasoline declined 75 percent between 1975 and 1985, 80 percent of the decline took place in 1985.Correct answer is option 'B'. Can you explain this answer? tests, examples and also practice GMAT tests.
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