请教：答案为什么不是C？

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For sinus pain, three out of four hospitals give their patients Noves. So when you want the most effective painkiller for sinus pain, Noves is the one to choose.

which of the following, if true, most seriously undermines the advertisement's argument?

c. many drug manufacurers increase sales of their products to hospitals by selling these products to the hospitals at the lowest pricr the manufacturers can afford.

d.unlike some competing brands of painkillers, Novex is available from pharmacies without a doctor's prescription.

我觉得答案是C才对啊，因为低价所以医院才用这种药，而不是因为effective.

怎么会是D呢？without a doctor's prescription 并不能削弱四分之三的医院开noves的事实啊，怎么能削弱该广告呢？

如果按照allanhzkk所言，

D的答案也蛮恶心的：N容易获得，柜台上销路好；然后医院看到有利可图就去大量进这个药卖给病人——给人治病不是看疗效而是考虑效益，医院好黑啊！

Argument Evaluation

Situation       An advertisement claims that Novex is the most effective painkiller for sinus pain since three out of four hospitals use it for patients.

Reasoning What point undermines the advertisement's claim? The argument for Novex's effectiveness as a painkiller is based upon the hospitals' usage. Consider what might be driving the hospitals' choice of medications to administer. Three out of four hospitals might be giving their patients Novex not because it is the most effective painkiller for sinus pain, but because it is inexpensive. If this is the case, the argument is seriously undermined.

A Other kinds of pain are irrelevant to the argument since the claim is only about sinus pain.

B This point does not undermine the advertisement's claim.

C Correct. This statement properly identifies a factor that could well undermine the advertisement's
claim: the hospitals may be using this medication because it is the most cost effective for them.

D Novex's nonprescription formula is not relevant to the claim.

E This point strengthens, rather than weakens, the claim. The correct answer is C.

正确答案是C，offcial guide上有。

我做的是新东方蓝皮的习题，书后面给的答案是错的。误导我。