LSAT Question Stem

The statements above, if true, support which one of the following inferences? 

Logical Reasoning Question Type

This is a Must Be True question. 

Correct Answer

The correct answer to this question is D. 

LSAT Question Complete Explanation

First, let's analyze the passage. In Yasukawa's study, smaller blackbirds had a higher survival rate than larger blackbirds over a month-long period. However, the author argues that Yasukawa's conclusion that size is a determinant of survival is probably mistaken, since smaller blackbirds are generally younger than larger ones. To simplify, imagine a study comparing the survival rate of small and large apples over a month. If smaller apples are generally younger, it might be the age of the apples, not their size, that affects their survival rate.

Now let's discuss the question type and answer choices. This is a Must Be True (MBT) question, which means we're looking for an inference that can be drawn from the statements in the passage.

a) This answer choice contradicts the passage, which states that smaller blackbirds are generally younger than larger ones. Therefore, there is a relation between size and age among the blackbirds that survived the study.

b) This answer choice cannot be inferred from the passage. We know that smaller blackbirds tend to be younger, but we don't have enough information to determine whether larger blackbirds of a given age are more likely to survive than smaller ones of the same age.

c) This answer choice is incorrect because it states that age doesn't make a difference among blackbirds of the same size. However, the passage suggests that age might be a more important factor than size in determining survival rates.

d) This is the correct answer. It states that among blackbirds of the same age, a difference in size may not indicate a difference in chances of survival over a month-long period. This supports the author's argument that Yasukawa's conclusion about size being a determinant of survival is probably mistaken.

e) This answer choice is not supported by the passage. We cannot infer that with a larger sample of blackbirds, the survival percentages of smaller and larger birds would be the same.

In summary, the correct answer is D because it aligns with the author's argument that Yasukawa's conclusion is probably mistaken, and it suggests that age, rather than size, might be a more important factor in determining survival rates among blackbirds.