OG12-23 CR

dreamlollipop

a drug that is highly effective in treating many types of infection can, at present , be obtained only from the bark of the ibora, a tree that is quite rare in the wild. it takes the bark of 5000 trees to make one kilogram of the drug. it follows, therefore, that continued production of the drug must inevitably lead to the ibora's extinction.

which of the following  most seriously weakens the argument above?

A.the drug made from ibora bark is dispensed to doctors from a central authority.
B. the drug made from ibara bark is expensive to produce
C. the leaves of the ibora are used in a number of medical products
D. the ibora can be propagated from cutting and grown under cultivation
E. the ibora generally grows in largely inaccessible places
答案是 D
请问C为什么不选？

liexodus

原文开头：a drug that is highly effective in treating many types of infection can 实质上已经将drug做限定，是用来治疗感染用的。

C. the leaves of the ibora are used in a number of medical products
   一些医药产品用ibora的叶子生产。
medical products是原文要的drug吗，没说清楚，需要ibora的叶子的量也没给出来，信息不足，没有作用的选项。

leslielu

叶子被用可能是主因，也可能不是，文章中没有明确，所以不如D直接有效地weaken。

lanshichao92

leaves是无关选项，应该排除，并且我们也不知道ibora的叶子也是丰富的

gmatvictors

bark of ibora才是炼药的原材料，跟C中的leaves无关，所以C是由irrelevant来排除的