#24 - It is widely believed that lancelets-small, primitive

[al_godnessmary]

Why is C not a better answer than D?

This is how I see the stem playing out:

resembles structure + resembles contractions is a heart

C - mentions both structures and "actions," which I took to be a twist on "contractions"; also mentions only "other animals" but that is consistent with the stem's wording for contractions, so I didn't consider that a point against C

D - if this is the correct answer, I clearly diagrammed incorrectly, because this says heart contractions

Was I then not supposed to give too much weight to "After all, it strongly resembles..." and only focus on the "moreover" part of the stem? Can someone please help shed some light on this? Thanks!

[Nikki Siclunov]

Hi al_godnessmary,

First off, this is a sufficient assumption question (otherwise known as a Justify question), not a necessary assumption question. Second, answer choice (C) is indeed the correct answer choice:

• Premise (1) and (2): The lancelet's vessel has structure and function that resemble those of other animal hearts.
  
  Conclusion: The lancelet has a heart.

Answer choice (C) is correct, because it establishes the connection between the premises and the conclusion as a conditional relationship between the two: if the premise is true, the conclusion must also be true.

Answer choice (D), meanwhile, states an assumption that underlies the reasoning here: the author clearly assumes that muscular contractions are one of the properties inherent to the function of the heart. However, just because this function is necessary for an organ to be considered a heart doesn't mean that it's sufficient to prove that the organ is a heart. (Smooth muscle is responsible for the contractility of pretty much all hollow organs, such as blood vessels, the gastrointestinal tract, the bladder, or the uterus.). Answer choice (D) would be the correct answer choice to an assumption question, but it falls short of justifying the conclusion.

Hope this helps!