aditya8062 wrote:According to a theory advanced by researcher Paul Martin, the wave of species extinctions that occurred in North America about 11,000 years ago, at the end of the Pleistocene era, can be directly attributed to the arrival of humans, i.e., the Paleoindians, who were ancestors of modern Native Americans. However, anthropologist Shepard Krech points out that large animal species vanished even in areas where there is no evidence to demon-strate that Paleoindians hunted them.Nor were extinctions confined to large animals: small animals, plants, and insects disappeared, presumably not all through human consumption. Krech also contradicts Martin's exclusion of climatic change as an explanation by asserting that widespread climatic change did indeed occur at the end of the Pleistocene. Still, Krech attributes secondary if not primary responsibility for the extinctions to the Paleoindians, arguing that humans have produced local extinctions elsewhere.

Which of the following, if true, would most weaken Krech's objections to Martin's theory?

A. Further studies showing that the climatic change that occurred at the end of the Pleistocene era was even more severe and widespread than was previously believed
B. New discoveries indicating that Paleoindians made use of the small animals, plants, and insects that became extinct
C. Additional evidence indicating that widespread climatic change occurred not only at the end of the Pleistocene era but also in previous and subsequent eras

D. Researchers' discoveries that many more species became extinct in North America at the end of the Pleistocene era than was previously believed
E. New discoveries establishing that both the arrival of humans in North America and the wave of Pleistocene extinctions took place much earlier than 11,000 years ago

ALSO how do we eliminate C?

GMATGuruNY wrote:

aditya8062 wrote:According to a theory advanced by researcher Paul Martin, the wave of species extinctions that occurred in North America about 11,000 years ago, at the end of the Pleistocene era, can be directly attributed to the arrival of humans, i.e., the Paleoindians, who were ancestors of modern Native Americans. However, anthropologist Shepard Krech points out that large animal species vanished even in areas where there is no evidence to demon-strate that Paleoindians hunted them.Nor were extinctions confined to large animals: small animals, plants, and insects disappeared, presumably not all through human consumption. Krech also contradicts Martin's exclusion of climatic change as an explanation by asserting that widespread climatic change did indeed occur at the end of the Pleistocene. Still, Krech attributes secondary if not primary responsibility for the extinctions to the Paleoindians, arguing that humans have produced local extinctions elsewhere.

Which of the following, if true, would most weaken Krech's objections to Martin's theory?

A. Further studies showing that the climatic change that occurred at the end of the Pleistocene era was even more severe and widespread than was previously believed
B. New discoveries indicating that Paleoindians made use of the small animals, plants, and insects that became extinct
C. Additional evidence indicating that widespread climatic change occurred not only at the end of the Pleistocene era but also in previous and subsequent eras

D. Researchers' discoveries that many more species became extinct in North America at the end of the Pleistocene era than was previously believed
E. New discoveries establishing that both the arrival of humans in North America and the wave of Pleistocene extinctions took place much earlier than 11,000 years ago

Note:
The passage above is not CR but RC.

Martin's conclusion:
The wave of species extinctions can be directly attributed to the Paleoindians.
Krech's conclusion:
Because the extinctions were not confined to large animals -- because small animals, plants, and insects also disappeared -- the wave of species extinctions CANNOT be attributed to the Paleoindians.

Krech assumes that the Paleoindians did not use the small animals, plants and insects that disappeared at the end of the Pleistocene period.
B: The Paleoindians made use of the small animals, plants, and insects that became extinct.
This answer choice attacks Krech's assumption, WEAKENING his conclusion that the wave of extinctions cannot be attributed to the Paleoindians.

The correct answer is B.

ALSO how do we eliminate C?

From the passage:
By asserting that widespread climatic change did indeed occur at the end of the Pleistocene, Krech contradicts Martin's exclusion of climatic change as an explanation.
In other words, Krech attributes the wave of extinctions to CLIMATE CHANGE.
C: Additional evidence indicating that widespread climatic change occurred not only at the end of the Pleistocene era but also in previous and subsequent eras.
This answer choice STRENGTHENS Krech's contention that the wave of extinctions can be attributed to climate change.
Eliminate C.

aiming800 wrote:Hi GmatGuru,

My doubt here is about the bold part,highlighted in red

small animals, plants, and insects disappeared, presumably not all through human consumption.

When Krech mentions the phrase highlighted in red above doesn't he already assumes that some of the consumption of those small animals,plants and insects are because of the humans,may be not to an extent that humans are the reason for their extinction,but to some extent. If yes, then isn't B strengthening what Krech already assumes,which is that some of the consumption of those small animals,plants and insects are because of the humans.

Could you please clarify.

Regards,
aiming 800

GMATGuruNY wrote:

aiming800 wrote:Hi GmatGuru,

My doubt here is about the bold part,highlighted in red

small animals, plants, and insects disappeared, presumably not all through human consumption.

When Krech mentions the phrase highlighted in red above doesn't he already assumes that some of the consumption of those small animals,plants and insects are because of the humans,may be not to an extent that humans are the reason for their extinction,but to some extent. If yes, then isn't B strengthening what Krech already assumes,which is that some of the consumption of those small animals,plants and insects are because of the humans.

Could you please clarify.

Regards,
aiming 800

OA: New discoveries indicating that Paleoindians MADE USE of the small animals, plants, and insects that became extinct.
The OA does NOT state that the Paleoindians CONSUMED the extinct species.
Rather, it states that the Paleoindians MADE USE of these species.
This information WEAKENS Krech's conclusion that the extinctions cannot be attributed to the arrival of humans.