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

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jabhatta2

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07 Feb 2022, 17:16

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Tried to create an analogy to see why option D is wrong

Quote:

Given more tourists in Canada this year --> Canada has low COVID cases

Weaken

(option Z) Canada gave out more tourist visas than usual this year
(option Z1) Canada reduced tourst visa fees to 0 dollars

Would these be weakeners ? I dont think (Z) and (Z1) would be weakeners , but i am not able to explain why exactly. (Z) and (Z1) are tempting for some reason.

Weakener is something that says -- GIVEN the premise has happened (For whatever reason it has) -- how can the conclusion STILL be false.

I think option Z and Z1 are tempting because it does explain the premise and gives ANOTHER reason (more visas or 0 $ visa fees) for the premise. I think our brains are then saying -- well if Z is true and the premise is also true -- how can you make the conclusion that you make to begin with. I think thats what going in my head atleast

But i dont think a weakener works like that.

I think a weakener in my analogy is

(option X) Tourists have COVID but are jabbed so no impact on anyone.

I think thats why D is wrong in the original problem.

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08 Feb 2022, 11:45

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jabhatta2

Tried to create an analogy to see why option D is wrong

Given more tourists in Canada this year --> Canada has low COVID cases

Your analogy is overly simplistic, jabhatta2, and that's causing you to spin around in circles.
The original argument's structure is quite complex. We have an argument that is offered in refutation of the environmentalists’ prediction. That's a mouthful. Take some time to digest what's going on here. There's a prediction made by environmentalists, but the author believes that their prediction is wrong, and he or she is attempting to convince us that indeed the environmentalists’ prediction is wrong.

So, what is their prediction?
The world’s Merrick population would decline as a result of the spill.

jabhatta2

Premise - the number of adult female Merricks returning to lay their eggs at Baker's Beach has actually increased somewhat since five years ago
option D, i thought provided support for this premise

No, option D doesn't provide support for this premise. This premise describes a surprising, unexpected phenomenon.

Option D, in a vacuum, provides a possible explanation for that phenomenon. However, we're not in a vacuum. We know that the chemical spill:

Quote:

prevented nearly all the eggs laid that year from hatching

Given that, the surprising, unexpected phenomenon remains unexplained when we read D. With eggs that won't hatch, what difference does it make whether they get eaten or not?

gmatimothy

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05 Jun 2022, 14:17

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stevegt

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?

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

We need to attack the conclusion by saying that the chemical spill led to a population decline.

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.

This informs that the premise that is supporting the conclusion is faulty. If the female turtles returning today are from 10 years ago, which is before the major chemical spill, the author's conclusion is broken because spill doesn't have anything to do with the increase.

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.

It doesn't matter whether the the birds that prey on the eggs decreased or not. We won't know if that led to an increase in the female turtles that came back without making more assumptions. Therefore, (D) is inferior to (B)

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.

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14 Aug 2022, 18:15

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GMATNinja can you help with an explanation? I'm struggling to see why (D) is incorrect. I felt it offered a different explanation that would weaken the argument if true. Thanks in advance!

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01 Sep 2022, 13:17

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justinandtobey

GMATNinja can you help with an explanation? I'm struggling to see why (D) is incorrect. I felt it offered a different explanation that would weaken the argument if true. Thanks in advance!

Did you see this post? Check it out and let us know if you have any further questions!

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10 Dec 2023, 06:51

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Understanding the argument -
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. Fact
Yet the number of adult female Merricks returning to lay their eggs at Baker’s Beach has actually increased somewhat since five years ago. "Yet" introduces the contrast, and this is a Fact.
Clearly, environmentalists’ prediction that the world’s Merrick population would decline as a result of the spill has proven unfounded. - Conclusion. "environmentalists’ prediction has proven unfounded"

Option Elimination - Weaken the conclusion.

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. - Facts respected. The argument clearly says the spill "prevented nearly all the eggs laid that year from hatching." Challenging the facts is not the scope of GMAT arguments.

B. Female Merrick sea turtles begin returning to Baker’s Beach to lay their eggs when they are ten years old. - ok. So, those impacted five years ago will show the results/come back, if any, five years from now.

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. Are we saying that with the chemical spill, more sea turtles survive somehow? At best, it's the opposite of what we need.

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's going in a direction that the population of sea turtles may increase. But wait, the scope of our argument is to weaken the conclusion, which is "environmentalists’ prediction that the world’s Merrick population would decline as a result of the spill has proven unfounded." So, we are primarily concerned about the chemical spill and its effect on sea turtles. This option talks about some other variable that is not even in the scope of the argument. Out of scope.

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. - out of scope.

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23 Jun 2024, 22:21

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stevegt

Premises:

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.

Conclusion:

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

Since five years after the spill, the population is the same (or even a bit more), the author is claiming that environmentalists’ prediction that the population would decline as a result of the spill is unfounded. We need to weaken the claim of the author i.e. we need to say that the environmentalists’ prediction could be accurate. The prediction is not unfounded. We need to say that the world’s Merrick population may decline as a result of the spill.

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.  

We are given that the spill prevented nearly all the eggs laid that year from hatching. Whether they were present at the time of the spill or were laid later is irrelevant.  

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

After the eggs hatch, the turtles enter the sea. How many turtles are in the sea, we cannot say. We gauge the number based on how many females show up to lay the eggs.  The turtles coming right now to lay eggs are those that were born ten years ago.  One entire year’s eggs were lost due to the spill so after ten years we will see the impact of fewer female turtles coming to lay eggs. Hence the author’s claim that environmentalists’ prediction is unfounded based on the number of females coming to lay eggs at this time (5 years after the spill) may not be correct.
Correct.

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.  

Whatever may be the actual number of females coming to lay eggs, the number is higher than that of five years ago. That is all we care about.  

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.  

We know that the number of females coming to lay the eggs has increased somewhat. What has been the impact of the spill and what has been the impact of fewer predators, we don’t know. Perhaps fewer predators has led to the increase and the spill had no impact. Perhaps the spill had a huge impact but fewer predators more than made up for it - we don’t know.   

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.  

Irrelevant to our argument. We already know that nearly all the eggs laid that year did not hatch.

Answer (B)

Discussion on Weaken Questions: https://youtu.be/EhZ8FKkfy0k

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15 Jul 2026, 04:44

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Excellent replies everyone. I know devastating decrease in population would be seen after 10 years of the accident as the correct answer states. The only part which is still bothering me is why the population increase? Why are we assuming the population of turtles has increased even though it is before the spill which are currently returning? It could be be same, could be little less or could be more.

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Hi iamyogi25,

You've got the 10-year timing exactly right, so let's clear up the one thing still nagging you.

Here's the key: we're not assuming the population increased - the argument tells us it did. Look at the second sentence of the stimulus:

"the number of adult female Merricks returning to lay their eggs at Baker's Beach has actually increased somewhat since five years ago."

That's a premise - a stated fact. In CR, you accept premises as true and reason from them; you don't get to say "it could be the same or a little less." The author has handed you the increase as given.

Where B fits

B doesn't fight that fact at all. It accepts that more females are showing up - and then explains why that fact is useless as evidence. Since females only return at age 10, every turtle laying eggs right now was born before the spill. So the increase is a real, true increase - it just reflects a pre-spill generation and tells us nothing about whether the spill hurt the population. That damage sits in the generation born the year of the spill, which won't return until about five years from now.

So your instinct "it could be same or less" is actually pointing at the same insight from a different angle: the current number, whatever it is, isn't a valid measure of the spill's effect. But you don't need to doubt the increase to reach that - you just note that the increase comes from the wrong batch of turtles.

Quick way to keep premises and assumptions separate: if the stimulus states it outright ("has increased"), it's a fact you build on. If you have to supply it to make the logic work, that's the assumption. Here, the increase is the author's fact; the hidden assumption is that this increase reflects the spill's effect - and B is what breaks that.

Answer: B

iamyogi25