A major chemical spill occurred five years ago at Baker’s Beach, the

Question

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.

EMPOWERgmatAllenT · Accepted Answer

Hi,

Let me highlight some of the key facts from the prompt first:

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?

Goal:   
 We need to weaken the argument attempting to disprove environmentalists' claim that the sea turtle population would decline  (put that another way: we need to show that the sea turtle population could still be harmed by the spill).

B. Female Merrick sea turtles begin returning to Baker’s Beach to lay their eggs
when they are ten years old.

If the turtles return when they're 10, then we have a scenario that shows that what's happening right now in no way can be used as a measure of the health of the sea turtle population. With this answer the turtles from the year of the spill could have been decimated, but the number of turtles right now could be bigger than ever if what we're seeing right now are those returning after 10 years.

If you'd like some additional follow up let me know. I'd be happy to help.

JarvisR · Answer

Hi,

Below is my reasoning for B. Initially I also got stumped by B .
Regards.
Conclusion: 
 environmentalists’ prediction that  the world’s Merrick population would decline as a result of the spill has proven unfounded . 
Premise:
1. 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.  
2. Yet  the number of adult female Merricks returning to lay their eggs at Baker’s Beach has actually increased somewhat since five years ago .
Assumption:These turtles are from the same batch that survived 5 years ago on Baker's Beach.
Weakener: What if these are not from that batch.Then that way environmentalist argument wont be broken and hence author conclusion wold be weaken.

Which of the following, if true, most seriously undermines the argument offered in refutation of the environmentalists’ prediction?
B does that.
If Female Merrick sea turtles begin returning to Baker’s Beach to lay their eggs when they are ten years old , then they are not from the same batch. They must be from an earlier batch and hence they were not impacted from the accident on Baker's Beach 5 years ago.

mikemcgarry · Answer

Dear Nevernevergiveup , I'm happy to respond. :-)

This is a truly brilliant question, like many of the official questions. Let's agree that choices (A) & (C) & (D) & (E) do not do the job: we can eliminate those. We know there was an oil spill five years ago, killing all the eggs then. In other words, all the Merrick sea turtles that would have been born five years ago were wiped out. Obviously, that's bad. Then, we find out, since that spill (and I guess a clean-up project?), the number of female Merrick sea turtles coming to lay eggs has increased. OK, the juxtaposition of these two facts raise an interest question. How old does a female Merrick sea turtle have to be before she starts reproducing? If a 1 or 2 year old female Merrick sea turtle were old enough to reproduce & lay eggs, and if five years after the spill, more and more are coming to lay eggs, it would seem that the population already has rebounded from that accident. That would be great! Instead, consider what (B) says: Female Merrick sea turtles begin returning to Baker’s Beach to lay their eggs when they are ten years old . Let's say the spill happened five years ago, in 2011. The female turtles who came to Baker’s Beach in the next year, 2012, were born in 2002 or before. The ones who came in 2013 were born in 2003 or before. Even this year, 2016, the turtles who come to lay eggs were born in 2006 or before. All the currently egg-laying turtles were born well before the spill. This means we haven't yet seen the reproductive "shadow" cast by the spill. The current egg-laying turtles were all born before the accident. The turtles who would have been born in 2011, the year of the accident, would not have started laying eggs until 2021: that's when we may see the effect of that missing generation of sea turtles. We simply wouldn't be seeing this population gap yet, because turtles born in 2011 would still be in some part of the extended turtle childhood, still five years away from reproducing. Thus, the evidence that the environmentalists are citing is irrelevant. Any turtles that have come to lay eggs over the last five years were born well before the accident. The absence of the ones who died in the accident will be felt later, starting about 10 years after the accident, or five year from now. In terms of the Merrick sea turtle population, the worst is yet to come, and what we have seen so far doesn't indicate the full impact of the accident. What's happening right now in terms of current egg-layers reflects births well before the spill, so we have not gotten to the point in time yet when the killed turtles would have started to reproduce. We have not seen the full reproductive impact of the accident yet. Does all this make sense? Mike :-)

bkk145 · Answer

This is B.
The assumption here is that last year's hatching affect the number of turtle this year.
If turtles only come back when they are 10 years old, then last year's hatching will not affect the number of turtle.

gmatavenue · Answer

Unplugged you are right about the Q but I don't agree with the assumptions.

Argument Construction:

Conclusion: Environmentalists are wrong.
Environmentalists: The Turtle population will reduce.

Question : Which of the following, if true, most  seriously undermines the argument  offered in  refutation  of the  environmentalists’ prediction ?

Argument offered in refutation environmentalists’ prediction : Number Female turtles increase --> Population Of Turtle has increased -->Environmentalists are wrong.

Refuted Argument offered in refutation environmentalists’ prediction : Number Female turtles increased due to some OTHER cause --> It does not guaranty that the Population Of Turtle has increased --> The Environmentalists may be right.

Also, another way was to show that the population of Turtles have decreased , u c. But there is no option indicating that....

OK about assumptions, 
For example we had Spillage in 1980.
After 5 yrs 1985 , Female turtles returning to lay eggs who were born in 1975. 
Now we may assume that number of Female turtles born increased from 1970 - 1975, but as it is mentioned the beach is only place to lay eggs we are not going out of scope. The fact that we select this option "B" provides a alternate explanation why Female Turtle increased.

If option said the Female Turtle return in 3 yrs, doest is explain anything. No. As it would mean
that Environmentalists are wrong as more eggs hatched from 1982 !

frankida · Answer

I thought the answer is B.

Because a chemical spill occurred five years ago and turtles are returning to lay eggs on the beach, we can conclude that turtle population is unaffected by the spill.

If it takes 10 years to get to maturity and return to the beach to lay eggs, then turtles unaffected by the spill would return. Therefore, the environmentalist's drawn conclusion could still be true.

samusa · Answer

A- Contradicts the information in the passage. 
B- We need to weaken the refutation. This option is plausible since it gives a reason to believe that indeed the eggs did not hatch and the returning females were actually born almost 5 years before the spill and thus remained unaffected.These females do not represent any successful hatching of eggs after the spill .
C-Irrelevant. Does not refute the prediction in any way. Instead it slightly strengthens the refutation.
D-Irrelevant. Does not refute the prediction in any way. Instead strengthens the refutation.
C-Irrelevant. Does not refute the prediction in any way. Instead it slightly strengthens the refutation.

Anu26 · Answer

B!

To prove : the population HAS INDEED come down (and will go down in future)

B proves that females take 10 years to return thus proving that the number of females who returned now would be born 10 years before thus we 
cannot make judgement based on the number returned this year.

Divyadisha · Answer

Author's Conclusion:- Environmentalist's prediction is unfounded. Prediction of E's- turtle population will decline. What we have to prove:- E's prediction is not unfounded. Or E is probably right in the prediction. Looking at the argument, we see that there are few facts:- -Oil spill occurred 5 years ago -BB is the ONLY ground for MT - Oil spill prevented nearly ALL eggs from hatching Surprising fact:- MT still return to lay its eggs at the BB (She is not aware of the oil spill, it seems

. The site is disastrous for the eggs) But wait! Where are these turtles coming from? Nearly ALL eggs vanished 5 years ago and continue to prevent hatching eggs further. The only reason could be that these females coming to lay their eggs here were born before oil spill. They will lay the eggs, which in turn will be vanished by oil, leading to decreased turtle population and supporting E's prediction. Few Possible strengtheners- 1) The Turtles, along with eggs, coming to lay its eggs will severely be affected by the oil in the water. 2) The conditions at the base of sea has not improved since past 5 years and nearly ALL eggs will continue to vanish. 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. This is just a piece of information , but it doesn't tell us what will be the effect on number of turtles in future. Also, it is mentioned in the argument that there were eggs (only then they can vanish). It seems a false information. B. Female Merrick sea turtles begin returning to Baker’s Beach to lay their eggs when they are ten years old. This is what one possible answer. These turtles will eventually die at certain old age and the eggs will anyway be vanished. 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. We are talking about abnormal conditions in the argument. 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. It makes us believe that if predator has declined , MT should increase. But it doesn't tell us the other way. 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. This is out of scope. Rejection doesn't mean that population will decline while their is increase in number of females going to the beach to lay eggs.

Nevernevergiveup · Answer

Source: Gmat prep Exampack 2

how can B be the correct answer? Lets us analyze the question part.

Which of the following, if true, most seriously undermines the argument offered in refutation of the environmentalists’ prediction?

or strengthen the environmentalist prediction?

Environmentalist predicted that Merrick population would decline as a result of the spill.

The argument disapproved it saying that since no of adult female Merricks returning to lay their eggs at Baker’s Beach has actually increased somewhat since five years ago, Merrick population did not decline because of the spill.

Inorder to address the question above either we have weaken the argument evidence regarding increase in adult female Merricks arrival or we have to prove that Merrick population decreased because of the spill.

I do not see any options doing the job and am clueless as to how OA does it.

rishabhdxt · Answer

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. 
Correct ; Since sea turtles come when they are 10 year old , the ill effects of chemical spill will be visible after 10 years.
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. 
 Highlighted part is the issue here. decline of 'one of the several species' will not have significant overall effect. ; incorrect

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.

melin94 · Answer

It's a sweet one! Check out Relationships in the argument.
IMO: Data Flaw Type
Conclusion: Environment's prediction is unproven.
Based on Premise: Some data -namely, increasing number of Merricks.
Weakener: What if the data is not representative? correct AC: Show that cited sample is from another data set (i.e. different Time Frame)

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.  Opposite - if this was true, the prediction would be false, and the author's conclusion would be true. 
B. Female Merrick sea turtles begin returning to Baker’s Beach to lay their eggs when they are ten years old.  Correct: This answer shows that the data sample (returning Merricks) are from a data set, that is actually not affected by the spill. So the author cannot base his conclusion on a different set of Merricks that have not been affected by the spill. Conclusion is has been weakened. 
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.  Irrelevant - Prediction could still be true 
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.   Out of scope - this AC clearly states that these pressure are UNRELATED TO THE CHEMICAL Spill, whereas the Predictions are based on the results of the spill (stated in the stimulus). So any other stuff unrelated to the spill is irrelevant. 
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 -  Clearly, irrelevant. If this answer choice had some effect, it would rather strengthen the author's conclusion, because if a group rejected to transfer eggs from the affected beach to a non-affected beach, one could assume that the spill had not have such a big effect, and thus the environmentalists' prediction are unfounded.

dabaobao · Answer

From all the posts in this thread, I do understand why B is the answer but I don't understand why D is wrong. D seems to provide an alternate explanation which could result in the increase in the turtles' population. I feel that D might be a better option than B.

GMATNinja · Answer

(D) tells us that the population of  one of the  several  species  of sea birds that prey on the turtle eggs has declined. Yes, this  might  (or might not) explain a slight increase in turtle survival rates and thus a slight increase in turtle population.

But remember that we are specifically looking for an answer choice that "seriously undermines  the argument offered in refutation of the environmentalists’ prediction ." What is that argument?

Nearly all of the eggs laid during the year of the spill failed to hatch. 
 Nevertheless, "the number of adult female Merricks returning to lay their eggs at Baker’s Beach has actually increased somewhat since five years ago." 
 According to the  author , the fact that the number of adult females returning to lay their eggs has increased is evidence that the turtle's population has NOT declined. 
 In other words, the author says, "Hey look, more adult females are returning to Baker's Beach, so the turtle population must not have declined."

We need an answer choice that undermines THAT specific line of reasoning. Sure, (D) provides a possible explanation for a population increase. But if we only explain a population increase, we have not hurt the author's argument.

If (D) were true, the author would say, "Fine, but if the population has increased, then the environmentalists were wrong." (D) simply offers a possible explanation for the evidence used in the author's argument (that there are more adult females returning to lay their eggs). But that doesn't affect that evidence or the conclusion drawn by the author based on that evidence. The environmentalists still seem to be wrong, and the author still seems to be right.

Since (D) does not undermine the author's argument, it should be eliminated.

gsingh0711 · Answer

The argument states that as a result of a chemical spill 5 years ago, it was predicted that the population of the Merrick Sea Turtles would decrease. However, the number of female Merricks who have returned to lay their eggs on the beach has increased over the last 5 years. Therefore, the author concludes that the prediction made by the environmentalists about the threat to the Merrick turtles caused by the oil spill. We need to weaken this conclusion. We need to prove that the oil spill has threatened the populations of the turtles.

If there were no turtles or eggs at that point, then it is probable that the spill did not do any damage to the Merricks. This may end up strengthening the author’s claim.
CORRECT. The Merricks return to hatch eggs only when they are 10 years old. But the spill occurred 5 years ago. Thus, the ones who are returning currently were already 5 years ago when the spill occurred. But the Merricks who could have been potentially affected by the spill would presently only be 5 years old. Thus, in order to figure out the exact nature of the damage done by the spill, we need to wait for another 5 years to know how many turtles actually return. The turtles who are presently return are not an accurate indicator of the damage done to the turtles.
‘Normal conditions’ is irrelevant.
If the creatures that prey on turtles have declined then it is possible that the number of turtles will also increase. This information, then, does not prove that chemical spill had a negative effect on the turtle population.
If the eggs were not transferred from the nearby beaches, then the fact remains that more turtles have returned over the last five years to lay their eggs. This may also strengthen the author’s claim.

I think, I deserve a kudus LOL

GDT · Answer

Pls explain why C is not correct

CrackverbalGMAT · Answer

Hi

Let me try to address your query. Let us first assess the conclusion and the premise on which it is based:

Conclusion:  Environmentalists’ prediction that the world’s Merrick population would decline as a result of the spill has proven unfounded.

Premises: 
i) A major chemical spill occurred five years ago at Baker’s Beach, and prevented nearly all the eggs laid that year from hatching.
ii) The number of adult female Merricks returning to lay their eggs at Baker’s Beach has actually increased somewhat since five years ago.

Therefore, we are looking for explanations that support environmentalists' predictions of a decline in the Merrick population, despite there being an increase in adult female turtles returning to lay eggs since five years ago. Let us examine option (C):

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.

This does not address what happened five years ago at all. If we assume that none of the eggs laid five years ago hatched, then none of the hatchlings would have survived (even fewer than normal). This does not explain how more adult turtles are returning to lay eggs now than five years ago. Hence, this does not undermine the conclusion made in the stimulus and is not the correct answer.

Hope this helps.

BhaveshGMAT · Answer

I had a tough time deciphering the question asked and thus ended up picking incorrect answer option, inspite of clearly understanding the stimulus.

So, here is my attempt. On such tough questions, we have to work backwards.

Which of the following, if true, most seriously undermines the argument offered in refutation of the environmentalists’ prediction?

(1) E's prediction: Turtle pop would decline
(2) argument refuting above : Turtle pop would not decline
(3) undermine above argument : Turtle pop would decline. - And this is what will the right answer option support.

Now the conclusion is - E's prediction is unfounded. So, therefore we now have to weaken the conclusion.

Only answer option B does so.

jabhatta2 · Answer

Isn't authors argument in the original question is in the format -- If X , Y

option D -- well X is definitely true

A major chemical spill occurred five years ago at Baker’s Beach, the

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Critical Reasoning (CR) Questions

A major chemical spill occurred five years ago at Baker’s Beach, the

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards