In Yasukawa's month–long study of blackbirds, the percentage of smaller birds that survived the duration of the study...

Sean on July 22, 2018

Please Explain

Could you explain why (D) is correct? Thank you!

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Mehran on July 23, 2018

Hi @smilde11, thanks for your post.

Let's start with the stimulus, as always. We have an argument here; the conclusion is "Yasukawa's conclusion that size is a determinant of a blackbird's chances of survival over a month-long period is probably mistaken." The premises provided in support of this claim are (1) that the percentage of smaller birds that survived the duration of the study exceeded the percentage of larger birds that survived, and (2) smaller blackbirds are generally younger than larger ones.

The question stem asks you to identify the answer choice that is most supported by the statements in the stimulus.

Answer choice (D) is correct. 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 is consistent with the information supplied in the stimulus, which tells you that Yasukawa's contrary conclusion "is probably mistaken." Put differently, the author of the stimulus sets out a claim that size probably does not determine a blackbird's chance of survival during a month-long period. The inference in answer (D) is, therefore, supported by the stimulus.

Hope this helps! Please let us know if you have any additional questions.