Q13 - Art theft from museums

[vswamy]

For question #13, I understood that the flaw in the reasoning was incorrect negation but I could not find the answer choice that made sense. Could you explain the wording of each answer choice? Thanks so much.

[ManhattanPrepLSAT1]

I think maybe you've misidentified the flaw...

Let's look at the argument closely. The evidence says that thieves steal what their customers are most interested in buying. The conclusion reached is that museums ought to focus their security on the most valuable pieces.

The argument possesses a gap...

the customers are most interested in buying the most valuable pieces.

The question asks us to find an assumption upon which the argument depends. Translation = Necessary Assumption

We want an answer choice that relates what the customers are interested in buying with which pieces are valuable. Answer choice (B) does give us this by suggesting the works that are in demand with the customers are the ones that are valuable.

(A) undermines the conclusion by suggesting that museums ought to focus their security on both valuable and invaluable works.
(B) is required for the conclusion to follow. If art pieces that were not very valuable were in demand by the customers, the conclusion reached in the argument would no longer make sense.
(C) is irrelevant. The distinction between secured and unsecured museums is not in play.
(D) supports the conclusion, but is not required for the conclusion to follow. How much of the security is devoted to valuable and invaluable art does not need to be precisely known.
(E) is irrelevant. The argument is about what thieves steal and sell, not what wealthy collectors sell.

I hope this helps clear things up. I'm nervous based on your understanding of the question stem, that maybe we're talking about different questions. Let me know!