Stacey Koprince wrote:This is a weaken question. Correct answers do not have to absolutely, without a doubt, in all circumstances weaken the conclusion. They only have to open up the possibility that the conclusion is not valid. The correct answer on a weaken question will typically accomplish this by introducing a new piece of information that calls into question an assumption made by the author.

Given -->75% of hospitals give patients Novex.

Claim --> Novex is most effective.

Assumption --> author assumes that effectiveness is the metric the hospitals use when deciding what medication to give.

Note --> the argument does not say WHY hospitals give patients Novex. We would all like to believe that they will choose based on the effectiveness of the medication, but that's not necessarily the case. We have no idea why these hospitals gave patients Novex. This is where the author's assumption comes in.

In order to weaken, the correct answer will open up the possibility that the hospitals use some other metric, not effectiveness, when deciding what medication to use.

And that's exactly what choice C does: the hospitals may be basing their decision on money, not effectiveness. That negatively affects the author's assumption that the hospitals must be deciding based upon effectiveness.

B talks about the 25% of the hospitals that don't give their patients Novex (at least to start). So, first, this is a minority (part of the author's argument was based on the behavior of the 75% majority). Second, if these 25% that don't start with Novex will then use Novex when the first medication doesn't work... if anything, that would seem to strengthen the author's assumption that Novex is the most effective. Perhaps that 25% uses some cheaper but inferior drug first and then switches to the more effective but more expensive Novex for those patients for whom the inferior drug fails.

More simply, though, B is out of scope because it's focusing on the 25% minority. The author isn't claiming that everyone uses Novex - only that it's the most effective because a majority uses it. Information about the minority doesn't affect that claim.