A drug that is highly efffective in treating many types of inflection 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 5,000 trees to make one kilogram of the drug. It follows, therefore, that continued production of the drug must inevitablely lead to the ibora's extinction.
which of the following, if true, most serious weakens the arguement above?
A The drug made from ibora bark is dispensed to doctors from a centual authority.
B The drug made from ibora bark is expensive to produce.
C The leaves of the ibora are used in a number of medical products.
D The ibora can be propageted from cuttings and grown under cultivation.
E The ibora generally grows in largely in accessible places.
The solution provided by OG is D.
i can undrstand, but C seems to be congenial to the logic of GMAT, i think.
because if other parts of the tree are used for other purpose, which leads to the extinction of the tree.
then the conclusion that the extinction is led by production of the drug seems to be weakened.
who couold tell me why not C, but D is the solution????
我是这样想的：要求找出most serious weakens，就要找具有“推翻”功能的选项。LZ已经接受要削弱“继续生产这种药物会导致这种植物绝种”是证明这种植物可以人工培植，野生的植物就不会再受砍伐......
那么再想想,C讲了另外一个加速这种植物绝种的可能，并不能削弱原文的“继续生产这种药物会导致这种植物绝种”，反而支持这种植物绝种的结论（所OG的解释是C“支持”原文）——打个比方，宣判了A犯人有罪，然后发现还有一个B共犯，能够减轻A的罪责吗？不能！反而是更加证实对A的审判是正确的。
不才谬论，不要扔番茄过来......
我认为：takes the bark of 5,000 trees to make one kilogram of the drug〉〉〉continued production of the drug must inevitablely lead to the ibora's extinction， 1kg药要5000树〉〉〉继续生产药树会灭绝， 削弱要说明这树不会灭绝，没影响。 C说了叶子，与题无关
请指正！
C which says the leaves of Ibra are now widely used in some other medical fields.
However, the argument is saying that the highly needs of bark of the Ibra will cause an extinction of this plants.
Even though the leaves of ibra are highly required, it still can not make any strike on the chain of this logical thread which strats from bark to the extiction.
The usage of the leaves is out of the scope of this question and logical thread.
Futher more, we can't say that it is the drug demand causes the extiction of the plants but the needs of the trees instead would be much more accurate from the point of author's view .
不好意思，我ARGUE一下。
拿你说的那个例子来说吧，
如果A有罪，那么发现B也是共犯，如果是这样了，发现A有罪，然后发现主要责任在B，是不是就可以认为这就削弱了A的罪责呢？ 望指教！
我的逻辑是：
生产D=》树灭绝
削弱：生产D不会使树灭绝
C：叶子用于。。 无关
我觉得那个犯人的例子应该这么来说：
说：A杀了个人，会导致他判死刑。
又有人说：A还犯过强奸罪呢！
能推翻结论吗？ 不能！
只有说，杀人并不是他判死刑的原因，强奸了N个人才是。如果不强奸，最多死缓！！这才能推翻结论。
C是不能推翻结论的。人家并没有表明以上那个关于死刑和死缓的逻辑关系。也就是说即使树叶被使用了，而且也能导致灭绝，也不能推翻结论。何况，题干并没有表明树叶对树的影响。（如果那个A就只是另外随地吐过痰了）。
啰嗦一大堆，不知道说清楚了没有。用了个什么杀人，强奸之类的词来说明廷不好意思的。但觉得就这样才能说清楚。
我觉得这题为条件型结论:结论带条件（即为充分必要）。WEAKEN的方法显示充分条件成立，必要条件可以不成立。
条件:continued production
结论:the ibora will extinction
WEAKEN的方法:continued production
但是the ibora will not extinction.推出D
我个人认为：
C在说明树的叶子都可以被使用---->这种树有的更大应用--->灭绝就更快了， 具有加强的意思（削弱应该是某种作用是这种树不会灭绝）
所以C错，个人之见
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