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The pronghorn, an antelope-like mammal that lives on the western plains of North America, is the continent’s fastest land animal, capable of running 90 kilometers per hour and of doing so for several (5) kilometers. Because no North American predator is nearly fast enough to chase it down, biologists have had difficulty explaining why the pronghorn developed its running prowess. One biologist, however, has recently claimed that pronghorns run as (10) fast as they do because of adaptation to predators known from fossil records to have been extinct for 10,000 years, such as American cheetahs and long- legged hyenas, either of which, it is believed, were fast enough to run down the pronghorn.(15) Like all explanations that posit what is called a relict behavior—a behavior that persists though its only evolutionary impetus comes from long-extinct environ- mental conditions—this one is likely to meet with skep- ticism. Most biologists distrust explanations positing relict (20) behaviors, in part because testing these hypotheses is so difficult due to the extinction of a principal component. They typically consider such historical explanations only when a lack of alternatives forces them to do so. But present-day observations sometimes yield (25) evidence that supports relict behavior hypotheses.In the case of the pronghorn, researchers have identified much supporting evidence, as several aspects of pronghorn behavior appear to have been shaped by enemies that no longer exist. For example, (30) pronghorns—like many other grazing animals—roam in herds, which allows more eyes to watch for predators and diminishes the chances of any particular animal being attacked but can also result in overcrowding and increased competition for food. But, since (35) pronghorns have nothing to fear from present-day carnivores and thus have nothing to gain from herding, their herding behavior appears to be another adaptation to extinct threats. Similarly, if speed and endurance were once essential to survival, researchers would (40) expect pronghorns to choose mates based on these athletic abilities, which they do—with female pronghorns, for example, choosing the victor after male pronghorns challenge each other in sprints and chases.Relict behaviors appear to occur in other animals (45) as well, increasing the general plausibility of such a theory. For example, one study reports relict behavior in stickleback fish belonging to populations that have long been free of a dangerous predator, the sculpin. In the study, when presented with sculpin, these (50) stickleback fish immediately engaged in stereotypical antisculpin behavior, avoiding its mouth and swimming behind to bite it. Another study found that ground squirrels from populations that have been free from snakes for 70,000 to 300,000 years still clearly recognize (55) rattlesnakes, displaying stereotypical antirattlesnake behavior in the presence of the snake. Such fear, however, apparently does not persist interminably. Arctic ground squirrels, free of snakes for about 3 million years, appear to be unable to recognize the (60) threat of a rattlesnake, exhibiting only disorganized caution even after being bitten repeatedly.Based on the passage, the term “principal component” (line 21) most clearly refers to which one of the following?a)behavior that persists even though the conditions that provided its evolutionary impetus are extinctb)the original organism whose descendants’ behavior is being investigated as relict behaviorc)the pronghorn’s ability to run 90 kilometers per hour over long distancesd)the environmental conditions in response to which relict behaviors are thought to have developede)an original behavior of an animal of which certain present-day behaviors are thought to be modificationsCorrect 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 pronghorn, an antelope-like mammal that lives on the western plains of North America, is the continent’s fastest land animal, capable of running 90 kilometers per hour and of doing so for several (5) kilometers. Because no North American predator is nearly fast enough to chase it down, biologists have had difficulty explaining why the pronghorn developed its running prowess. One biologist, however, has recently claimed that pronghorns run as (10) fast as they do because of adaptation to predators known from fossil records to have been extinct for 10,000 years, such as American cheetahs and long- legged hyenas, either of which, it is believed, were fast enough to run down the pronghorn.(15) Like all explanations that posit what is called a relict behavior—a behavior that persists though its only evolutionary impetus comes from long-extinct environ- mental conditions—this one is likely to meet with skep- ticism. Most biologists distrust explanations positing relict (20) behaviors, in part because testing these hypotheses is so difficult due to the extinction of a principal component. They typically consider such historical explanations only when a lack of alternatives forces them to do so. But present-day observations sometimes yield (25) evidence that supports relict behavior hypotheses.In the case of the pronghorn, researchers have identified much supporting evidence, as several aspects of pronghorn behavior appear to have been shaped by enemies that no longer exist. For example, (30) pronghorns—like many other grazing animals—roam in herds, which allows more eyes to watch for predators and diminishes the chances of any particular animal being attacked but can also result in overcrowding and increased competition for food. But, since (35) pronghorns have nothing to fear from present-day carnivores and thus have nothing to gain from herding, their herding behavior appears to be another adaptation to extinct threats. Similarly, if speed and endurance were once essential to survival, researchers would (40) expect pronghorns to choose mates based on these athletic abilities, which they do—with female pronghorns, for example, choosing the victor after male pronghorns challenge each other in sprints and chases.Relict behaviors appear to occur in other animals (45) as well, increasing the general plausibility of such a theory. For example, one study reports relict behavior in stickleback fish belonging to populations that have long been free of a dangerous predator, the sculpin. In the study, when presented with sculpin, these (50) stickleback fish immediately engaged in stereotypical antisculpin behavior, avoiding its mouth and swimming behind to bite it. Another study found that ground squirrels from populations that have been free from snakes for 70,000 to 300,000 years still clearly recognize (55) rattlesnakes, displaying stereotypical antirattlesnake behavior in the presence of the snake. Such fear, however, apparently does not persist interminably. Arctic ground squirrels, free of snakes for about 3 million years, appear to be unable to recognize the (60) threat of a rattlesnake, exhibiting only disorganized caution even after being bitten repeatedly.Based on the passage, the term “principal component” (line 21) most clearly refers to which one of the following?a)behavior that persists even though the conditions that provided its evolutionary impetus are extinctb)the original organism whose descendants’ behavior is being investigated as relict behaviorc)the pronghorn’s ability to run 90 kilometers per hour over long distancesd)the environmental conditions in response to which relict behaviors are thought to have developede)an original behavior of an animal of which certain present-day behaviors are thought to be modificationsCorrect 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 pronghorn, an antelope-like mammal that lives on the western plains of North America, is the continent’s fastest land animal, capable of running 90 kilometers per hour and of doing so for several (5) kilometers. Because no North American predator is nearly fast enough to chase it down, biologists have had difficulty explaining why the pronghorn developed its running prowess. One biologist, however, has recently claimed that pronghorns run as (10) fast as they do because of adaptation to predators known from fossil records to have been extinct for 10,000 years, such as American cheetahs and long- legged hyenas, either of which, it is believed, were fast enough to run down the pronghorn.(15) Like all explanations that posit what is called a relict behavior—a behavior that persists though its only evolutionary impetus comes from long-extinct environ- mental conditions—this one is likely to meet with skep- ticism. Most biologists distrust explanations positing relict (20) behaviors, in part because testing these hypotheses is so difficult due to the extinction of a principal component. They typically consider such historical explanations only when a lack of alternatives forces them to do so. But present-day observations sometimes yield (25) evidence that supports relict behavior hypotheses.In the case of the pronghorn, researchers have identified much supporting evidence, as several aspects of pronghorn behavior appear to have been shaped by enemies that no longer exist. For example, (30) pronghorns—like many other grazing animals—roam in herds, which allows more eyes to watch for predators and diminishes the chances of any particular animal being attacked but can also result in overcrowding and increased competition for food. But, since (35) pronghorns have nothing to fear from present-day carnivores and thus have nothing to gain from herding, their herding behavior appears to be another adaptation to extinct threats. Similarly, if speed and endurance were once essential to survival, researchers would (40) expect pronghorns to choose mates based on these athletic abilities, which they do—with female pronghorns, for example, choosing the victor after male pronghorns challenge each other in sprints and chases.Relict behaviors appear to occur in other animals (45) as well, increasing the general plausibility of such a theory. For example, one study reports relict behavior in stickleback fish belonging to populations that have long been free of a dangerous predator, the sculpin. In the study, when presented with sculpin, these (50) stickleback fish immediately engaged in stereotypical antisculpin behavior, avoiding its mouth and swimming behind to bite it. Another study found that ground squirrels from populations that have been free from snakes for 70,000 to 300,000 years still clearly recognize (55) rattlesnakes, displaying stereotypical antirattlesnake behavior in the presence of the snake. Such fear, however, apparently does not persist interminably. Arctic ground squirrels, free of snakes for about 3 million years, appear to be unable to recognize the (60) threat of a rattlesnake, exhibiting only disorganized caution even after being bitten repeatedly.Based on the passage, the term “principal component” (line 21) most clearly refers to which one of the following?a)behavior that persists even though the conditions that provided its evolutionary impetus are extinctb)the original organism whose descendants’ behavior is being investigated as relict behaviorc)the pronghorn’s ability to run 90 kilometers per hour over long distancesd)the environmental conditions in response to which relict behaviors are thought to have developede)an original behavior of an animal of which certain present-day behaviors are thought to be modificationsCorrect answer is option 'D'. Can you explain this answer?.

Solutions for The pronghorn, an antelope-like mammal that lives on the western plains of North America, is the continent’s fastest land animal, capable of running 90 kilometers per hour and of doing so for several (5) kilometers. Because no North American predator is nearly fast enough to chase it down, biologists have had difficulty explaining why the pronghorn developed its running prowess. One biologist, however, has recently claimed that pronghorns run as (10) fast as they do because of adaptation to predators known from fossil records to have been extinct for 10,000 years, such as American cheetahs and long- legged hyenas, either of which, it is believed, were fast enough to run down the pronghorn.(15) Like all explanations that posit what is called a relict behavior—a behavior that persists though its only evolutionary impetus comes from long-extinct environ- mental conditions—this one is likely to meet with skep- ticism. Most biologists distrust explanations positing relict (20) behaviors, in part because testing these hypotheses is so difficult due to the extinction of a principal component. They typically consider such historical explanations only when a lack of alternatives forces them to do so. But present-day observations sometimes yield (25) evidence that supports relict behavior hypotheses.In the case of the pronghorn, researchers have identified much supporting evidence, as several aspects of pronghorn behavior appear to have been shaped by enemies that no longer exist. For example, (30) pronghorns—like many other grazing animals—roam in herds, which allows more eyes to watch for predators and diminishes the chances of any particular animal being attacked but can also result in overcrowding and increased competition for food. But, since (35) pronghorns have nothing to fear from present-day carnivores and thus have nothing to gain from herding, their herding behavior appears to be another adaptation to extinct threats. Similarly, if speed and endurance were once essential to survival, researchers would (40) expect pronghorns to choose mates based on these athletic abilities, which they do—with female pronghorns, for example, choosing the victor after male pronghorns challenge each other in sprints and chases.Relict behaviors appear to occur in other animals (45) as well, increasing the general plausibility of such a theory. For example, one study reports relict behavior in stickleback fish belonging to populations that have long been free of a dangerous predator, the sculpin. In the study, when presented with sculpin, these (50) stickleback fish immediately engaged in stereotypical antisculpin behavior, avoiding its mouth and swimming behind to bite it. Another study found that ground squirrels from populations that have been free from snakes for 70,000 to 300,000 years still clearly recognize (55) rattlesnakes, displaying stereotypical antirattlesnake behavior in the presence of the snake. Such fear, however, apparently does not persist interminably. Arctic ground squirrels, free of snakes for about 3 million years, appear to be unable to recognize the (60) threat of a rattlesnake, exhibiting only disorganized caution even after being bitten repeatedly.Based on the passage, the term “principal component” (line 21) most clearly refers to which one of the following?a)behavior that persists even though the conditions that provided its evolutionary impetus are extinctb)the original organism whose descendants’ behavior is being investigated as relict behaviorc)the pronghorn’s ability to run 90 kilometers per hour over long distancesd)the environmental conditions in response to which relict behaviors are thought to have developede)an original behavior of an animal of which certain present-day behaviors are thought to be modificationsCorrect 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 pronghorn, an antelope-like mammal that lives on the western plains of North America, is the continent’s fastest land animal, capable of running 90 kilometers per hour and of doing so for several (5) kilometers. Because no North American predator is nearly fast enough to chase it down, biologists have had difficulty explaining why the pronghorn developed its running prowess. One biologist, however, has recently claimed that pronghorns run as (10) fast as they do because of adaptation to predators known from fossil records to have been extinct for 10,000 years, such as American cheetahs and long- legged hyenas, either of which, it is believed, were fast enough to run down the pronghorn.(15) Like all explanations that posit what is called a relict behavior—a behavior that persists though its only evolutionary impetus comes from long-extinct environ- mental conditions—this one is likely to meet with skep- ticism. Most biologists distrust explanations positing relict (20) behaviors, in part because testing these hypotheses is so difficult due to the extinction of a principal component. They typically consider such historical explanations only when a lack of alternatives forces them to do so. But present-day observations sometimes yield (25) evidence that supports relict behavior hypotheses.In the case of the pronghorn, researchers have identified much supporting evidence, as several aspects of pronghorn behavior appear to have been shaped by enemies that no longer exist. For example, (30) pronghorns—like many other grazing animals—roam in herds, which allows more eyes to watch for predators and diminishes the chances of any particular animal being attacked but can also result in overcrowding and increased competition for food. But, since (35) pronghorns have nothing to fear from present-day carnivores and thus have nothing to gain from herding, their herding behavior appears to be another adaptation to extinct threats. Similarly, if speed and endurance were once essential to survival, researchers would (40) expect pronghorns to choose mates based on these athletic abilities, which they do—with female pronghorns, for example, choosing the victor after male pronghorns challenge each other in sprints and chases.Relict behaviors appear to occur in other animals (45) as well, increasing the general plausibility of such a theory. For example, one study reports relict behavior in stickleback fish belonging to populations that have long been free of a dangerous predator, the sculpin. In the study, when presented with sculpin, these (50) stickleback fish immediately engaged in stereotypical antisculpin behavior, avoiding its mouth and swimming behind to bite it. Another study found that ground squirrels from populations that have been free from snakes for 70,000 to 300,000 years still clearly recognize (55) rattlesnakes, displaying stereotypical antirattlesnake behavior in the presence of the snake. Such fear, however, apparently does not persist interminably. Arctic ground squirrels, free of snakes for about 3 million years, appear to be unable to recognize the (60) threat of a rattlesnake, exhibiting only disorganized caution even after being bitten repeatedly.Based on the passage, the term “principal component” (line 21) most clearly refers to which one of the following?a)behavior that persists even though the conditions that provided its evolutionary impetus are extinctb)the original organism whose descendants’ behavior is being investigated as relict behaviorc)the pronghorn’s ability to run 90 kilometers per hour over long distancesd)the environmental conditions in response to which relict behaviors are thought to have developede)an original behavior of an animal of which certain present-day behaviors are thought to be modificationsCorrect answer is option 'D'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of The pronghorn, an antelope-like mammal that lives on the western plains of North America, is the continent’s fastest land animal, capable of running 90 kilometers per hour and of doing so for several (5) kilometers. Because no North American predator is nearly fast enough to chase it down, biologists have had difficulty explaining why the pronghorn developed its running prowess. One biologist, however, has recently claimed that pronghorns run as (10) fast as they do because of adaptation to predators known from fossil records to have been extinct for 10,000 years, such as American cheetahs and long- legged hyenas, either of which, it is believed, were fast enough to run down the pronghorn.(15) Like all explanations that posit what is called a relict behavior—a behavior that persists though its only evolutionary impetus comes from long-extinct environ- mental conditions—this one is likely to meet with skep- ticism. Most biologists distrust explanations positing relict (20) behaviors, in part because testing these hypotheses is so difficult due to the extinction of a principal component. They typically consider such historical explanations only when a lack of alternatives forces them to do so. But present-day observations sometimes yield (25) evidence that supports relict behavior hypotheses.In the case of the pronghorn, researchers have identified much supporting evidence, as several aspects of pronghorn behavior appear to have been shaped by enemies that no longer exist. For example, (30) pronghorns—like many other grazing animals—roam in herds, which allows more eyes to watch for predators and diminishes the chances of any particular animal being attacked but can also result in overcrowding and increased competition for food. But, since (35) pronghorns have nothing to fear from present-day carnivores and thus have nothing to gain from herding, their herding behavior appears to be another adaptation to extinct threats. Similarly, if speed and endurance were once essential to survival, researchers would (40) expect pronghorns to choose mates based on these athletic abilities, which they do—with female pronghorns, for example, choosing the victor after male pronghorns challenge each other in sprints and chases.Relict behaviors appear to occur in other animals (45) as well, increasing the general plausibility of such a theory. For example, one study reports relict behavior in stickleback fish belonging to populations that have long been free of a dangerous predator, the sculpin. In the study, when presented with sculpin, these (50) stickleback fish immediately engaged in stereotypical antisculpin behavior, avoiding its mouth and swimming behind to bite it. Another study found that ground squirrels from populations that have been free from snakes for 70,000 to 300,000 years still clearly recognize (55) rattlesnakes, displaying stereotypical antirattlesnake behavior in the presence of the snake. Such fear, however, apparently does not persist interminably. Arctic ground squirrels, free of snakes for about 3 million years, appear to be unable to recognize the (60) threat of a rattlesnake, exhibiting only disorganized caution even after being bitten repeatedly.Based on the passage, the term “principal component” (line 21) most clearly refers to which one of the following?a)behavior that persists even though the conditions that provided its evolutionary impetus are extinctb)the original organism whose descendants’ behavior is being investigated as relict behaviorc)the pronghorn’s ability to run 90 kilometers per hour over long distancesd)the environmental conditions in response to which relict behaviors are thought to have developede)an original behavior of an animal of which certain present-day behaviors are thought to be modificationsCorrect answer is option 'D'. Can you explain this answer?, a detailed solution for The pronghorn, an antelope-like mammal that lives on the western plains of North America, is the continent’s fastest land animal, capable of running 90 kilometers per hour and of doing so for several (5) kilometers. Because no North American predator is nearly fast enough to chase it down, biologists have had difficulty explaining why the pronghorn developed its running prowess. One biologist, however, has recently claimed that pronghorns run as (10) fast as they do because of adaptation to predators known from fossil records to have been extinct for 10,000 years, such as American cheetahs and long- legged hyenas, either of which, it is believed, were fast enough to run down the pronghorn.(15) Like all explanations that posit what is called a relict behavior—a behavior that persists though its only evolutionary impetus comes from long-extinct environ- mental conditions—this one is likely to meet with skep- ticism. Most biologists distrust explanations positing relict (20) behaviors, in part because testing these hypotheses is so difficult due to the extinction of a principal component. They typically consider such historical explanations only when a lack of alternatives forces them to do so. But present-day observations sometimes yield (25) evidence that supports relict behavior hypotheses.In the case of the pronghorn, researchers have identified much supporting evidence, as several aspects of pronghorn behavior appear to have been shaped by enemies that no longer exist. For example, (30) pronghorns—like many other grazing animals—roam in herds, which allows more eyes to watch for predators and diminishes the chances of any particular animal being attacked but can also result in overcrowding and increased competition for food. But, since (35) pronghorns have nothing to fear from present-day carnivores and thus have nothing to gain from herding, their herding behavior appears to be another adaptation to extinct threats. Similarly, if speed and endurance were once essential to survival, researchers would (40) expect pronghorns to choose mates based on these athletic abilities, which they do—with female pronghorns, for example, choosing the victor after male pronghorns challenge each other in sprints and chases.Relict behaviors appear to occur in other animals (45) as well, increasing the general plausibility of such a theory. For example, one study reports relict behavior in stickleback fish belonging to populations that have long been free of a dangerous predator, the sculpin. In the study, when presented with sculpin, these (50) stickleback fish immediately engaged in stereotypical antisculpin behavior, avoiding its mouth and swimming behind to bite it. Another study found that ground squirrels from populations that have been free from snakes for 70,000 to 300,000 years still clearly recognize (55) rattlesnakes, displaying stereotypical antirattlesnake behavior in the presence of the snake. Such fear, however, apparently does not persist interminably. Arctic ground squirrels, free of snakes for about 3 million years, appear to be unable to recognize the (60) threat of a rattlesnake, exhibiting only disorganized caution even after being bitten repeatedly.Based on the passage, the term “principal component” (line 21) most clearly refers to which one of the following?a)behavior that persists even though the conditions that provided its evolutionary impetus are extinctb)the original organism whose descendants’ behavior is being investigated as relict behaviorc)the pronghorn’s ability to run 90 kilometers per hour over long distancesd)the environmental conditions in response to which relict behaviors are thought to have developede)an original behavior of an animal of which certain present-day behaviors are thought to be modificationsCorrect answer is option 'D'. Can you explain this answer? has been provided alongside types of The pronghorn, an antelope-like mammal that lives on the western plains of North America, is the continent’s fastest land animal, capable of running 90 kilometers per hour and of doing so for several (5) kilometers. Because no North American predator is nearly fast enough to chase it down, biologists have had difficulty explaining why the pronghorn developed its running prowess. One biologist, however, has recently claimed that pronghorns run as (10) fast as they do because of adaptation to predators known from fossil records to have been extinct for 10,000 years, such as American cheetahs and long- legged hyenas, either of which, it is believed, were fast enough to run down the pronghorn.(15) Like all explanations that posit what is called a relict behavior—a behavior that persists though its only evolutionary impetus comes from long-extinct environ- mental conditions—this one is likely to meet with skep- ticism. Most biologists distrust explanations positing relict (20) behaviors, in part because testing these hypotheses is so difficult due to the extinction of a principal component. They typically consider such historical explanations only when a lack of alternatives forces them to do so. But present-day observations sometimes yield (25) evidence that supports relict behavior hypotheses.In the case of the pronghorn, researchers have identified much supporting evidence, as several aspects of pronghorn behavior appear to have been shaped by enemies that no longer exist. For example, (30) pronghorns—like many other grazing animals—roam in herds, which allows more eyes to watch for predators and diminishes the chances of any particular animal being attacked but can also result in overcrowding and increased competition for food. But, since (35) pronghorns have nothing to fear from present-day carnivores and thus have nothing to gain from herding, their herding behavior appears to be another adaptation to extinct threats. Similarly, if speed and endurance were once essential to survival, researchers would (40) expect pronghorns to choose mates based on these athletic abilities, which they do—with female pronghorns, for example, choosing the victor after male pronghorns challenge each other in sprints and chases.Relict behaviors appear to occur in other animals (45) as well, increasing the general plausibility of such a theory. For example, one study reports relict behavior in stickleback fish belonging to populations that have long been free of a dangerous predator, the sculpin. In the study, when presented with sculpin, these (50) stickleback fish immediately engaged in stereotypical antisculpin behavior, avoiding its mouth and swimming behind to bite it. Another study found that ground squirrels from populations that have been free from snakes for 70,000 to 300,000 years still clearly recognize (55) rattlesnakes, displaying stereotypical antirattlesnake behavior in the presence of the snake. Such fear, however, apparently does not persist interminably. Arctic ground squirrels, free of snakes for about 3 million years, appear to be unable to recognize the (60) threat of a rattlesnake, exhibiting only disorganized caution even after being bitten repeatedly.Based on the passage, the term “principal component” (line 21) most clearly refers to which one of the following?a)behavior that persists even though the conditions that provided its evolutionary impetus are extinctb)the original organism whose descendants’ behavior is being investigated as relict behaviorc)the pronghorn’s ability to run 90 kilometers per hour over long distancesd)the environmental conditions in response to which relict behaviors are thought to have developede)an original behavior of an animal of which certain present-day behaviors are thought to be modificationsCorrect answer is option 'D'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice The pronghorn, an antelope-like mammal that lives on the western plains of North America, is the continent’s fastest land animal, capable of running 90 kilometers per hour and of doing so for several (5) kilometers. Because no North American predator is nearly fast enough to chase it down, biologists have had difficulty explaining why the pronghorn developed its running prowess. One biologist, however, has recently claimed that pronghorns run as (10) fast as they do because of adaptation to predators known from fossil records to have been extinct for 10,000 years, such as American cheetahs and long- legged hyenas, either of which, it is believed, were fast enough to run down the pronghorn.(15) Like all explanations that posit what is called a relict behavior—a behavior that persists though its only evolutionary impetus comes from long-extinct environ- mental conditions—this one is likely to meet with skep- ticism. Most biologists distrust explanations positing relict (20) behaviors, in part because testing these hypotheses is so difficult due to the extinction of a principal component. They typically consider such historical explanations only when a lack of alternatives forces them to do so. But present-day observations sometimes yield (25) evidence that supports relict behavior hypotheses.In the case of the pronghorn, researchers have identified much supporting evidence, as several aspects of pronghorn behavior appear to have been shaped by enemies that no longer exist. For example, (30) pronghorns—like many other grazing animals—roam in herds, which allows more eyes to watch for predators and diminishes the chances of any particular animal being attacked but can also result in overcrowding and increased competition for food. But, since (35) pronghorns have nothing to fear from present-day carnivores and thus have nothing to gain from herding, their herding behavior appears to be another adaptation to extinct threats. Similarly, if speed and endurance were once essential to survival, researchers would (40) expect pronghorns to choose mates based on these athletic abilities, which they do—with female pronghorns, for example, choosing the victor after male pronghorns challenge each other in sprints and chases.Relict behaviors appear to occur in other animals (45) as well, increasing the general plausibility of such a theory. For example, one study reports relict behavior in stickleback fish belonging to populations that have long been free of a dangerous predator, the sculpin. In the study, when presented with sculpin, these (50) stickleback fish immediately engaged in stereotypical antisculpin behavior, avoiding its mouth and swimming behind to bite it. Another study found that ground squirrels from populations that have been free from snakes for 70,000 to 300,000 years still clearly recognize (55) rattlesnakes, displaying stereotypical antirattlesnake behavior in the presence of the snake. Such fear, however, apparently does not persist interminably. Arctic ground squirrels, free of snakes for about 3 million years, appear to be unable to recognize the (60) threat of a rattlesnake, exhibiting only disorganized caution even after being bitten repeatedly.Based on the passage, the term “principal component” (line 21) most clearly refers to which one of the following?a)behavior that persists even though the conditions that provided its evolutionary impetus are extinctb)the original organism whose descendants’ behavior is being investigated as relict behaviorc)the pronghorn’s ability to run 90 kilometers per hour over long distancesd)the environmental conditions in response to which relict behaviors are thought to have developede)an original behavior of an animal of which certain present-day behaviors are thought to be modificationsCorrect answer is option 'D'. Can you explain this answer? tests, examples and also practice GMAT tests.