Recently, scientists determined that great white sharks can live over

Question

Recently, scientists determined that great white sharks can live over 70 years, much longer than had been previously thought. They made the discovery by examining the layers of different colors that accumulated on the shark's teeth over the years. In the 1950s, atomic bomb testing produced unusually large amounts of carbon-14, which fell from the atmosphere into the ocean and accumulated as a distinctive layer on the shark's teeth corresponding to a known period in time. Perplexingly, even though great white sharks live longer than had been expected, some parties maintain that based on the new findings, the great white sharks must be protected from overfishing.

Which of the following, if true, best resolves the discrepancy identified above?

A. Great white sharks need to be protected from overfishing because they are dying rapidly due to poisoning by carbon-14.

B. Great white sharks were determined to live longer than had been previously thought based on the discovery of a carbon-14-rich layer within older sharks' teeth.

C. Great white sharks are evidently endangered and therefore need to be protected from overfishing.

D. Some great white sharks may have rich layers of carbon-14 from other sources, depending on their migration patterns.

E. Great white sharks' longer lifespan implies that they mature more slowly and reproduce more slowly than had previously been assumed.

daagh · Accepted Answer

Explanation from GMAT FREE, the source

Reading the question: We have a long prompt and a short stem, so we check the stem. It says "resolve a discrepancy." That's the same as "explain." As discussed in Osprey Prey and Caller Complaints, since we are explaining, we should identify the two parts of the so-called "discrepancy." The correct answer will need to address both parts, without contradicting any of the facts given.

Creating a filter: "Perplexingly" is an important word, because it allows us to parse the prompt into two parts. The second, shorter part is that sharks must be protected from overfishing. Why is that perplexing? Because of whatever the main point of the first part is: sharks live longer than expected. We'll look for something that connects logically to both parts: 1) sharks live longer than expected, and 2) they must be protected.

Applying the filter: (A) doesn't connect to the sharks' age. Choice (B) just restates part of the prompt. Choice (C) just restates the other part of the prompt. Choice (D) doesn't connect to either portion of the discrepancy. Choice (E) touches on both parts: it says that if sharks are older than we thought, there are fewer of them than we thought. That's a good reason to protect them from overfishing.

Logical proof: A logical proof is not always possible on "explain" questions, but we can use the negation test to confirm (E), in this case. Suppose that sharks reproduced more quickly than had previously been assumed: that would lessen the need to protect sharks. Since the negation would add to the mystery and contradict the opinion of "some parties," we have confirmation the non-negated (E) would, indeed, resolve the mystery. The correct answer is (E).

Dabhishek · Answer

Great white sharks need to be protected from overfishing because they are dying rapidly due to poisoning by carbon-14. no mention about poisoning. Don't know Cant say DKCS

Great white sharks were determined to live longer than had been previously thought based on the discovery of a carbon-14-rich layer within older sharks' teeth. dont explain desipency

Great white sharks are evidently endangered and therefore need to be protected from overfishing. fact but not explaining the descrepancy

Some great white sharks may have rich layers of carbon-14 from other sources, depending on their migration patterns. OFS

Great white sharks' longer lifespan implies that they mature more slowly and reproduce more slowly than had previously been assumed. correctly giving the relation between lifespan and overfishing

IMO E

Guilio · Answer

E is the best answer, though I would have one question regarding D.

Would it be totally out of scope to assume that because "some great white sharks may have rich layers of carbon-14 from other sources," they might not live longer after all (since layers of carbon-14 were the main evidence for sharks' longer lifetime). If so, then the population might actually have decreased and therefore the overfishing must be taken under control. 
This would in essence refute the accepted fact and it is probably out of scope. I was just wondering whether my reasoning was completely false in that case?

I chose E as well though, but it took me a while to cross off D.

Thank you guys for your help, 
Jay

mvictor · Answer

only E gives a valid reason to protect the sharks from overfishing.
A - not true. evidence of C14 on shark's teeth from 1950 - so not actually poisoning..
B - that is stated in the argument, and doesn't help to explain the paradox
C - evidently? how? very vague..so not good.
D - other sources of C14 is out of scope.
E - looks good.

warriorguy · Answer

Boiled down to C and E.

Evidently in C seemed too extreme. There is nothing in the stem that seems to point that evidently they are endangered.

Hence E.

My assumption was that - sharks need to be protected from overfishing because their fodder - (other fishes) - is getting depleted and hence they are dying since they are not getting any food to eat even though they can live longer than expected :D

colorblind · Answer

Ans is E, but this part of the explanation posted by  daagh  sums it up well:

himanshurajawat · Answer

I'm facing difficulty in understanding why 'C' is preferred over 'E'. Can anyone explain the answer?

GMATNinja   gmat1393   GMATNinja Two  nightblade354   Bunuel   VeritasKarishma

AkshdeepS · Answer

I'm facing difficulty in understanding why 'C' is preferred over 'E'. Can anyone explain the answer?

himanshurajawat

Hi,

E is the correct answer, therefore E is preferred to C and not vice - versa.

himanshurajawat · Answer

AkshdeepS

Thanks for the reply. I wanted to know the reasoning behind it.

Posted from my mobile device

AkshdeepS · Answer

himanshurajawat

Let us deal with C and E only :

C. Great white sharks are evidently endangered and therefore need to be protected from overfishing.

First of, passage does not support this assertion that GWS are evidently endangered. The premise that tells us about the production of large amount Carbon-14 by atomic bomb testing is used to describe the accumulation of distinctive layer on the sharks teeth. Passage nowhere says that C-14 is harmful. It just says C-14 accumulates on the teeth, and by the help of this accumulation we can assess the age of GWS. Therefore, we can not say GWS is endangered and need protection. This does not resolve the paradox.

For resolving paradox, correct answer must touch both the points in contention.

E. Great white sharks' longer lifespan implies that they mature more slowly and reproduce more slowly than had previously been assumed.

Now, E says , GWS has a longer life span as mentioned in first line of the passage (the first point of contention). But they mature slowly and therefore reproduce slowly. This means even after having a longer life span, their population may not be enough and must be needed to protect from overfishing (the second point of contention).

Hope it helps.

KarishmaB · Answer

Discovery: Great white sharks live longer than previously thought. 
Some parties maintain that  based on the new findings , the great white sharks must be protected from overfishing.

The argument specifically mentions 'based on the new findings', sharks must be protected.

So there must be something about living longer that endangers them. And that is the paradox. We need something that will explain it.

A. Great white sharks need to be protected from overfishing because they are dying rapidly due to poisoning by carbon-14.

Doesn't tell us how living longer endangers them.

B. Great white sharks were determined to live longer than had been previously thought based on the discovery of a carbon-14-rich layer within older sharks' teeth.

Doesn't tell us how living longer endangers them.

C. Great white sharks are evidently endangered and therefore need to be protected from overfishing.

Doesn't tell us how living longer endangers them.

D. Some great white sharks may have rich layers of carbon-14 from other sources, depending on their migration patterns.

Doesn't tell us how living longer endangers them.

E. Great white sharks' longer lifespan implies that they mature more slowly and reproduce more slowly than had previously been assumed.

Tells us how living longer endangers them. Because they mature more slowly and reproduce more slowly (than previously assumed), their population is at risk.

Answer (E)

Kushchokhani · Answer

KarishmaB

I marked choice D because I thought that acquiring carbon-14 from other sources means that it is not acquired from atomic bomb testing in the 1950s. Thereby, it directly resolves the paradox between live longer and protection from overfishing- how? if carbon-14 is not acquired in the 1950s but say just 10 years back from other source, 70 years have not elapsed from 1950s till date of the question publication and hence sharks do not live longer than previously expected. Thereby, overfishing may endanger the population.

Then I realized the word "Some" at the very beginning of choice D. So, concluded that this choice needs to be ruled out.

My query- If "some" word wouldn't have been there, then could choice D help resolve the paradox basis my above understanding?

I hope this won't violate any facts as the passage just says that "scientists determined that great white sharks can live over 70 years basis their examination of teeth." So, its quite possible that the layer of carbon-14 on teeth may have been occurred from some other source only few years back.

KarishmaB · Answer

Note the last sentence of the argument:

Perplexingly, even though great white sharks live longer than had been expected, some parties maintain that based on the new findings, the great white sharks must be protected from overfishing.

The argument tells us that great white sharks live longer than had been expected (needs to be taken to be true)
The paradox is that based on the new findings, people are saying that the great white sharks must be protected from overfishing.

So questioning the method used to determine that great sharks live longer than had been expected will not help resolve the paradox. The point is why are people saying that they must be protected based on the new findings. Why do the new findings lead to more or renewed need for protection? 
That is explained by option (E). If they live longer, it means they mature slowly and hence reproduce slowly. Hence they make up their numbers slowly and need to be protected. It explains why people are asking for protection for white sharks based on the findings.

Hence option (D) is not the most suitable, with or without 'some.'

VerbalBot · Answer

Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.

Recently, scientists determined that great white sharks can live over

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

Recently, scientists determined that great white sharks can live over

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