Red admiral butterflies fly in a highly irregular fashion, constantly varying their speed, wing strokes, and flight p...

Mehran on October 10, 2017

Hi, no it's not a "Must Be True" question. It's a "Strengthen" question ("Which one of the following, if true, would most strengthen the astronomer's argument?").

Notice that the question stem is directing you to focus not on the text in the stimulus to find the right answer (which is often the case for Must Be True questions) but instead to the given answer choices (a hint that you're looking at a Strengthen question).

Hope this helps!

Anna on November 10, 2018

Why is the correct answer A and not E? I was between the two and I thought E was the better answer because the red admiral butterfly is not a poisonous butterfly.

Mehran on November 11, 2018

Hi @Anna, thanks for your post. Let's start, as always, with the stimulus. We have to be sure we have a solid grasp on the stimulus if we are to have a chance at selecting the correct answer choice.

This stimulus presents an argument. The conclusion is "Scientists therefore hypothesize that the red admiral's flight style, which is clearly not energy efficient, evolved as a means of avoiding predators." What premises are provided in support of this hypothesis? (1) Red admiral butterflies fly in a highly irregular fashion, (2) Red admirals are not poisonous, and (3) nonpoisonous butterflies need to elude predators to survive.

The word "hypothesis" indicates cause and effect reasoning. Here, the scientists believe the effect (the red admiral's irregular and inefficient flight style) is due to a specific cause (the aim of avoiding predators).

The question stem ask us to STRENGTHEN this hypothesis. Answer choice (A) bolsters the scientists' claim that a butterfly's irregular flight style is related to whether or not that butterfly is poisonous. This answer choice thus strengthens the cause and effect argument presented in the stimulus. This answer establishes that the red admiral butterfly's flight style is, in fact, distinct from the flight pattern of any poisonous butterfly species.

Answer choice (E) is irrelevant, because its focus is on the predators, rather than the red admiral butterfly itself. Whether or not the predators prey on other nonpoisonous butterflies does not do anything to help us a strengthen a hypothesis that is specific to this one nonpoisonous specie (the red admiral).

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