LSAT Explanation PT 38, S4, Q15: Loggerhead turtles live and breed in

LSAT Question Stem

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

Logical Reasoning Question Type

This is a Weaken question. 

Correct Answer

The correct answer to this question is D. 

LSAT Question Complete Explanation

We are given a Weaken question type for this LSAT problem. Our goal is to find the answer choice that most seriously weakens the reasoning presented in the passage.

First, let's analyze the argument in the passage. The passage states that new evidence suggests juvenile Pacific loggerheads that feed near the Baja peninsula hatch in Japanese waters 10,000 kilometers away. This is based on the premise that 95% of the DNA samples taken from the Baja turtles match those taken from turtles at the Japanese nesting sites. The conclusion of the argument is that Baja turtles hatch in Japanese waters.

To help understand this argument, imagine a simple example: two groups of students, one from School A and one from School B. If 95% of the students from School A have the same favorite color as the students from School B, the argument would be concluding that the students from School A must have originated from School B. We can see that this conclusion might not necessarily be true, even if the premise about the favorite color is accurate.

An "Evaluate" question for this argument could be: "Is there any other factor that could explain the 95% DNA match between Baja turtles and Japanese turtles?"

Now, let's examine each answer choice:

a) This answer choice does not directly impact the argument, as it only provides information about the location of other nesting sites without discussing their DNA similarity to the Baja turtles.

b) This answer choice is irrelevant to the argument, as it discusses the distance between nesting sites and feeding sites of Atlantic loggerhead turtles, which are not the focus of the passage.

c) This answer choice tries to weaken the argument by suggesting a discrepancy between the number of hatchlings in Japanese waters and the number of nesting sites near the Baja peninsula. However, it does not directly address the DNA evidence, which is the basis of the argument.

d) This is the correct answer choice. If 95% of the DNA samples taken from the Baja turtles match those taken from Atlantic loggerhead turtles, it shows that the 95% match with Japanese turtles is not necessarily indicative of their origin. This weakens the conclusion that Baja turtles hatch in Japanese waters.

e) This answer choice is irrelevant to the argument, as it discusses the breeding between Atlantic and Pacific loggerheads, which was not an issue in the passage.