Q14 - Certain methods of creating

[atzhang6v6]

isnt B just contrapositive of the conclusion? How can this be an assumention?

[ManhattanPrepLSAT1]

Well, assuming the conclusion were true, wouldn't that prove that the conclusion is true? My instinct says that's circular reasoning and invalid. But then I do have this nagging feeling that I've selected an answer choice on a Sufficient Assumption question that simply assumed the conclusion. I think, I'd select it, if I saw it. I can't think of a time where the conclusion restated was the wrong answer on a Sufficient Assumption question.

That said, in this case, the right answer is not the contrapositive of the conclusion.

If we're going to prevent counterfeits, we need to make some images on banknotes difficult to measure. Why? Because certain methods of making counterfeits involve making accurate measurements.

Answer choice (B) is a clever way of eliminating other ways to prevent the production of counterfeit banknotes. For example, if the methods of making counterfeit banknotes could be prevented by blocking another step in the process. It could be that there are several difficult steps in the methods discussed that involve accurate measurements.

Incorrect Answers
(A) is out of scope. Copying technology isn't discussed.
(C) undermines the argument. This diminishes the threat posed by counterfeiters.
(D) is out of scope. How many countries this issue affects does not relate to the means of correcting the issue.
(E) is out of scope. The amount of counterfeit money in circulation does not indicate whether new counterfeit money is entering circulation or the means of preventing it.

[atzhang6v6]

thank you for your reply.
so maybe the ・must・in the conclusion is the key to select B because if there are further or other steps, making it dofficult to measure may not a must thing to do?