In the new version of the core curriculum, the way JY teaches Argument Part questions, he tells us to beware of answer choices that use language like "assumption" or "implies" etc. because if the question states an idea explicitly mentioned in the stimulus, it by definition cannot be an assumption or implicit. This made a lot of sense to me and still does! However, PT39, S2, Q16 makes me struggle a bit. As the right answer calls the explicitly referenced idea "an assumption."
Attractive Wrong Answer: C - "It is offered as evidence for the contention that human beings must be descended from either lungfish or coelacanths."
Correct Answer: D - "It is an assumption that both parties to the dispute use as a starting point for their arguments about human evolution."
The question says "which one of the following most accurately describes the role played in the dispute above by the proposition that frogs are definitely related to the species of fish from which human beings evolved"
The stimulus says "Since biologists agree that frogs are definitely related to the species of fish from which human beings evolved..."
How could that idea possibly play an "assumption" role in the argument if it is explicitly stated?
I know the LSAT makes it pretty hard to hold any absolute truths about the test, but I really thought it would be hard to ever have a correct Argument Part answer choice reference an assumption. Am I totally off-base here? Thanks!