Advertisement:

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

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

(A) Some competing brands of painkillers are intended to reduce other kinds of pain in addition to sinus pain.

(B) Many hospitals that do not usually use Novex will do so for those patients who cannot rolerate the drug the hospitals usually use.

(C) Many drung manufacturers increase sales of their products to hospitals by selling these products to the hospitals at the lowest price the manufacturers can afford.

(D) Unlike some competing brands of painkillers, Novex is available from pharmacies without a doctor's prescription.

(E) In clinical trials Novex has been found more effective than competing brands of painkillers that have been on the market longer than Novex.

I picked "C" but correct answer is "D". Appreciated if anyone can advise!

楼主说的是XDF的新逻辑分册第182题吧：）

前提：3/4的医院都给得S病的人开N药

结论：N是最有效的治S病的药之一

C：Many drung manufacturers increase sales of their products to hospitals by selling these products to the hospitals at the lowest price the manufacturers can afford.--只能说明药价低，但结论关注的是N是否有效，因此无关

D：Unlike some competing brands of painkillers, Novex is available from pharmacies without a doctor's prescription. --说明医院开N药多是因为N药容易开（不需要医生的处方也可以买得到），而并不是因为N药效果好而多开，因此是它因解释前提“医院开N药多”，并削弱结论“N药有效”

欢迎讨论。