Loggerhead turtles live and breed in distinct groups, of which some ar

D creates that element of doubt that weaken the conclusion
some people might argue that D is contradicting the fact of the premise and that we are not allowed to do so but here is an answer to that :
fact is :Ninety-five percent of the DNA samples taken from the Baja turtles match those taken from turtles at the Japanese nesting sites

conclusion is : juvenile Pacific loggerheads that feed near the Baja peninsula hatch in Japanese waters 10,000 kilometers away

now what D does is it that tells us that even though Ninety-five percent of the DNA samples taken from the Baja turtles match those taken from turtles at the Japanese nesting sites still Ninety-five percent of the DNA samples taken from the Baja turtles match those taken from Atlantic loggerhead turtles.---->there by creating a scope for a fact that all these turtles might be effectively same and hence we cannot say with full authority that it is Pacific loggerheads that feed near the Baja peninsula that hatch in Japanese waters 10,000 kilometers away .who knows they might be from altantic
note that in weakening or strengthening questions we cannot contradict the fact of the premise !!

In first read, i got a little confused as how to go with the question, since the question stem itself is a little confusing.
But then i got more straight forward and blunt with the data answer choices were offering.

too many variables = in an exam secnarion , in time crunching situation too difficult to extract, if one can extract & then zone in nothing like that, if not POE ;

Skim through the stem : Feed in B / hatch in J ( DNA B = DNA J )

POE :

A : Nesting sites found in Pacific = Even if they are found in Egypt , what's in it for me = Eliminate

B: Nesting site = Feeding site Distance ( we are not here to solve a Time & Distance problem) = Eliminate

C : Hold = Speaks of Baja

D : Hold = Speaks of Baja

E : Aquariums = we are discussing 700-750 ( sea/Oceans ), where from this 300 score (Aquarium ) crops up = Eliminate

thus left with C n D :

C : Hatchlings decline in J ( may be Japan is stricter even with turtles wrt population control = Eliminate

D : Left with D = will mark n move & this is logical too ( In stem : B = J, Option D says B = A ; thus contradiction / Weaken )


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Thanks in advance.

--Peace--

OFFICIAL EXPLANATION

The argument uses the premise that Baja turtles and Japanese turtles share ninety-five percent of their DNA to conclude that Baja turtles hatch in Japanese waters 10,000 kilometers away. This sounds like convincing statistical evidence unless you realize that many organisms share DNA. For example, humans and chimpanzees share about 98% of their DNA (we share about 75% of our DNA with dogs, for that matter). Since Baja and Japanese turtles come from the same species, it is not surprising that they would share a high percentage of their DNA. Regardless of whether or not you saw this connection, you should have been skeptical of the reference to juvenile turtles traveling 10,000 kilometers. Such a lengthy trip by a juvenile animal is unlikely, and calls into question the soundness of the argument.

Answer choice (A): This answer does not impact the argument because no details—DNA or otherwise—are given about the turtles at these nesting sites off the Pacific coast of North America.

Answer choice (B): The fact that Atlantic turtles have nesting and feeding sites no more than 5,000 kilometers apart does not attack the argument because the argument is about Baja turtles.

Answer choice (C): This answer attempts to weaken the argument by inducing you to conclude that if the Japanese hatchlings are declining but Baja sites are constant, then the Baja sites cannot be supplied by the Japanese hatchlings. But, the answer choice moves from the number of hatchlings to the number of sites. Even with a declining number of hatchlings, the number of sites could remain constant, albeit with fewer turtles at each. Because of this possibility, the answer does not undermine the argument.

Answer choice (D): This is the correct answer. The answer shows that all turtles in the argument have the same ninety-five percent DNA, meaning that the Baja turtles did not have to take the 10,000 kilometer trip.

Answer choice (E): The breeding between species was not an issue in the stimulus.
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Premis: Ninety-five percent of the DNA samples taken from the Baja turtles match those taken from turtles at the Japanese nesting sites.

Conclusion: juvenile Pacific loggerheads that feed near the Baja peninsula hatch in Japanese waters 10,000 kilometers away.

Assumption: 95% of the DNA Sample match indicates that the Baja turtles and Turtles at Japanese nesting sites are the same.

Which one of the following, if true, most seriously weakens the reasoning above?

(A) Nesting sites of loggerhead turtles have been found off the Pacific coast of North America several thousand kilometers north of the Baja peninsula.we don't care about this

(B) The distance between nesting sites and feeding sites of Atlantic loggerhead turtles is less than 5,000 kilometers.

(C) Loggerhead hatching in Japanese waters have been declining in number for the last decade while the number of nesting sites near the Baja peninsula has remained constant.
this choice is among contenders at first glance, but we should bear in mind that loggerhead hatching and number of nesting sites are unrelated.

(D) Ninety-five percent of the DNA samples taken from the Baja turtles match those taken from Atlantic loggerhead turtles.

the fact that 95% of the DNA sample taken from B turtles match those of Atlantic turtles indicates that Atlantic turtles and Japanese ones have the same % of DNA match so it is absurd to conclude that they belongs to either places.

(E) Commercial aquariums have been successfully breeding Atlantic loggerheads with Pacific loggerheads for the last five years.

Assumption: No problem with DNA analysis exists (quality, interpretation, interfering factors etc.)

D describes such problem

KAPLAN EXPLANATION

(D) Weaken the Argument

Establishing an equally plausible, alternative hypothesis to the one advanced by the argument is a great way to weaken that argument. The “new evidence” that the Baja turtles hatch in Japanese waters is the DNA match of 95% of them with Japanese turtles. But if the Baja turtles match up equally well with Atlantic turtles, as (D) asserts, then it’s a 50/50 shot as to whether the Baja turtles hatch in Japan or the Atlantic—the evidence is equivalent either way.

(A), (B), (C), and (E) can all be quickly eliminated for one simple reason: None of them deals with the DNA match-up evidence, the one and only support provided for the initial claim that the Baja turtles hatch in Japan.
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Very confusing question and Im far from convinced.

It is given that Pacifics feed near Baja.

DNA 95 Baja matches DNA 95 Japan.

D says that DNA 95 Baja matches DNA 95 Atlantic.

But what if DNA 5 Baja matches DNA 5 Japan and also DNA 5 Pacific?!

Then this implies that DNA 95 is actually evidence that Pacific do hatch in Japan, because earlier we always found DNA 100 Japan to match DNA 100 Atlantic.

Think about that.

Posted from my mobile device

Nothing is said about 5% DNA samples that don't match. So, thinking about the rest of the samples would be a waste of time unless options offer something to look into.
We know that conclusion says Baja peninsula loggerheads hatch in Japanese waters for which a fact based reasoning is given which strengthens the conclusion elaborating 95% DNA samples match. Hence, a weakener must either give a fact about sample size or prove that the given fact is diluted in some sense.
D follows the latter and opens doors wherein the fact given in the argument is actually generic in nature. If 95% Baja DNA samples match with Atlantic samples then it is possible that those 95% Japanese DNA samples that match Baja might be from Atlantic.

Note: Baja is south to California, hence Baja = Pacific. However, you need not to know geography as passage aptly makes this understandable. The highlighted text seems to suggest that.

HTH.
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