Critical Reasoning

A major chemical spill occurred five years ago at Baker's Beach, the world's sole nesting ground for Merrick sea turtles, and prevented nearly all the eggs laid that year from hatching. Yet the number of adult female Merricks returning to lay their eggs at Baker's Beach has actually increased somewhat since five years ago. Clearly, environmentalists' prediction that the world's Merrick population would decline as a result of the spill has proven unfounded.
Which of the following, if true, most seriously undermines the argument offered in refutation of the environmentalists' prediction?
A. The chemical spill five years ago occurred at a time when there were neither Merrick sea turtles nor Merrick sea turtle eggs on Baker's Beach.
B. Female Merrick sea turtles begin returning to Baker's Beach to lay their eggs when they are ten years old.
C. Under normal conditions, only a small proportion of hatchling female Merrick sea turtles survive in the ocean until adulthood and return to lay their eggs at Baker's Beach.
D. Environmental pressures unrelated to the chemical spill have caused a significant decline in the population of one of the several species of sea birds that prey on Merrick sea turtle eggs.
E. After the chemical spill, an environmental group rejected a proposal to increase the Merrick sea turtle population by transferring eggs from Baker's Beach to
nearby beaches that had not been affected by the spill.

IMO B


if spill happened 5 yrs ago... and the female turtles come after 1o yrs..

then it can happen that when the spill happened the female turtles were
in sea and were not ready to lay eggs.. and are now returning to lay eggs from last 5 yrs..( increase in number
of turtles coming to Baker's beach )

but it doesn't mean the population is not impacted.. what happened to the eggs laid by them
from last 5 yrs ... ?? they could have died.. which supports scientists argument..

Whats the Oa..??

IMO D is the answer.

Prediction of environmentalist:Turtle population will decline.

Author's argument:Turtle population will not decline due to increase in no of egg laying turtles.

We need to undermine author's argument.The author is assuming that increase of egg laying turtles will lead to more no. of eggs hatching.This need not be the case.If there is some other reason due to which more no of eggs hatch, then this logic is weakened (Alternate cause for the same effect ). The alternate cause is decrease in no of predators which eat the eggs.

IMO B is incorrect because we dont know the age of turtles which are returning to hatch

What is the OA ?

IMO B

nervesofsteel wrote:IMO B


if spill happened 5 yrs ago... and the female turtles come after 1o yrs..

then it can happen that when the spill happened the female turtles were
in sea and were not ready to lay eggs.. and are now returning to lay eggs from last 5 yrs..( increase in number
of turtles coming to Baker's beach )

but it doesn't mean the population is not impacted.. what happened to the eggs laid by them
from last 5 yrs ... ?? they could have died.. which supports scientists argument..

Whats the Oa..??

B is indeed correct, although your reasoning is a bit shaky at the end.

The refutation of the prediction that turtle population wasn't negatively impacted is based off the current number of turtles returning to lay eggs. If B is true, then the current number of returning is irrelevant; we're concerned about the number of turtles who will return 10 years after the spill, which is still 5 years off in the future.

Since B makes us question the relevance of the refutation's evidence, it weakens the refutation.

IMO D
D shows that return is due to decline in the no. of the bird that prey on eggs and not due to decline in effect of spill (which counter claim to enviornmentalist's assumes)

Stuart Kovinsky wrote:

nervesofsteel wrote:IMO B


if spill happened 5 yrs ago... and the female turtles come after 1o yrs..

then it can happen that when the spill happened the female turtles were
in sea and were not ready to lay eggs.. and are now returning to lay eggs from last 5 yrs..( increase in number
of turtles coming to Baker's beach )

but it doesn't mean the population is not impacted.. what happened to the eggs laid by them
from last 5 yrs ... ?? they could have died.. which supports scientists argument..

Whats the Oa..??

B is indeed correct, although your reasoning is a bit shaky at the end.

The refutation of the prediction that turtle population wasn't negatively impacted is based off the current number of turtles returning to lay eggs. If B is true, then the current number of returning is irrelevant; we're concerned about the number of turtles who will return 10 years after the spill, which is still 5 years off in the future.

Since B makes us question the relevance of the refutation's evidence, it weakens the refutation.

Stuart,could you please let me know why D is incorrect,

Focus_gmat wrote:
Stuart,could you please let me know why D is incorrect,

Focus_gmat, do not focus on un-necessary quote where at the end you have to ask a tiny Q, some time your Q will not get focus because you focus to quote a whole bunch of text. Do you have problem in only typing your question , or referring your relevant part in quote.

For your question, the answer D is called something like Shell Game answers, i.e. touching the issues but because of very different reason, : Environment prediction is based on chemical spills, author point is not weakened because number of preys are less and so less number of turtles are killed, argument is concerned with decline in turtle population due to lack of turtle eggs hatches as happened due to chemical spill.

If you are reading options like D twice, go and reach a bunch of OG explanations, just explanations, to have a sense of atttractive(that include opposite as well as as shell game answers).

B seems to be the best choice here