Self-study
Books about architectural works, unless they are not intended for a general audience, ought to include discussions of both the utility and the aesthetic appeal of each of the buildings they consider. ██ ████ ██ ████ ████ ███ ███████ ██████████ ████ ██ ███████ ███████ ███████ █████████ █████ ██████████ ██████████ ████████ ███ █████ ██ ███████ ████ ███ ████ ████ ██ █ ██████ ██ █████████ ██ ██████ ███ █ ███████ ████ ██ ███ ██ ███ █████ ████████████ ████████████ ██ ███████ ████
Stimulus Summary
The stimulus starts with a general claim about books about architectural works: if they are for a general audience, they should discuss both the utility and the aesthetic appeal of each of the buildings they consider. If they fail to do this, they are flawed. We are then told about a specific book by Morton, which describes the functional aspects of Italian Baroque palaces, but does not mention the ceiling in the main hall of one of these palaces, which is one of the "masterpieces" of Western art.
Analysis: Necessary Assumption
If you noticed that the stimulus is almost set up as a rule-application scenario, where we're given a general rule to apply to a specific situation, you're onto something. The stimulus alone doesn't give us a conclusion, but the question stem tells us what conclusion we want to derive: that Morton's book is flawed.
With this conclusion in mind, the first assumption you might pre-phrase could be that, because Morton's book fails to mention this ceiling in one of the palaces, it fails to discuss the aesthetic appeal of at least one of the buildings it discusses, and is therefore flawed. But remember the pre-condition for any book about architecture to even fall under the rule in the stimulus: that the book must be for a general audience. If Morton's book is for a general audience, then learning whether failing to mention this ceiling counts as failing to discuss the aesthetic appeal of one of the buildings would help us conclude that the book is flawed. But if Morton's book is not for a general audience, then regardless of how egregious it is to leave out this ceiling, we can't conclude that the book is flawed. So a vital necessary assumption here is that Morton's book is for a general audience, and therefore falls under the rule the stimulus gives us.
6.
If the statements above are █████ ██ █████ ██ █████████ ██ █████████ █████ ███ ██ ███ █████████ ██ █████ ██ ████████ ████ ██████████ ████ ██ ███████
a
Morton’s description of ███ ██████████ ███████ ██ ███████████
Incorrect. Even if we negate this to say that Morton's description of the palaces' utility is not inaccurate — i.e., it is accurate — the book could still be flawed because, by failing to mention this particular ceiling, Morton has failed to discuss the aesthetic appeal of one of the palaces. So (A) isn't a necessary assumption.
b
Morton’s book does ███ ███████ ███████ ██ ███ ███████ █████ ████ ███████ ███ █████████ ███████
Incorrect. Even if we know a book is intended for a general audience (which we don't know about Morton's book), the only criterion given to us for the book not being flawed is that it discusses both the utility and aesthetic appeal of each of the buildings it considers. Whether the book includes or excludes other aspects of the buildings is irrelevant, as far as we know. So (B) isn't a necessary assumption.
c
Morton’s book is ████████ ███ █ ███████ █████████
Correct. Knowing this fact alone is not sufficient for us to conclude that Morton's book is flawed, but we need this to know that Morton's book even falls under the rule we are given. If we negate this to say that Morton's book is not intended for a general audience, then the rule we are given (the only way we know how to determine whether a book is flawed or not) doesn't apply to Morton's book. So (C) is a necessary assumption.
d
The passage discussing ███ ██████ █████ █ ████ █████████ ████ ██ ███████ ██ █████████ ███ ███████ ████████ ██ ██████████ █████
Incorrect. We don't know how the relative importance of a passage to the "overall argument" of a book impacts whether it is flawed or not. This criterion is never mentioned in the stimulus. Even if we negate (D) to say that this particular passage does not play an important role in helping to establish the overall argument of Morton's book, it could still be possible that Morton's book is flawed according to the rule we are given. So (D) is not a necessary assumption.
e
The palace discussed ██ ██████ ██ ███ ██ ███ ████ █████████████ █████████ ██ █████ ███████ ██ ██████████ █████
Incorrect. Even if we negate (E) to say that this palace is not one of the most aesthetically important of those treated in Morton's book, the rule says that for each of the buildings discussed, an architecture book must discuss both the utility and the aesthetic appeal. And if failing to mention this particular ceiling counts as not discussing the aesthetic appeal of this particular palace, Morton's book could still be flawed. Since negating (E) wouldn't destroy the argument, (E) isn't a necessary assumption.