刚考过的GWD-CR,答案寻求中?

,Q28:

Which of the following most logically completes the argument?

A certain cultivated herb is one of a group of closely related plants that thrive in soil with high concentrations of metals that are toxic to most other plants.  Agronomists studying the herb have discovered that it produces large amounts of histidine, an amino acid that, in test-tube solutions, renders these metals chemically inert.  Possibly, therefore, the herb’s high histidine production is what allows it to grow in metal-rich soils, a hypothesis that would gain support if ______.

1. histidine is found in all parts of the plant—roots, stem, leaves, and flowers
           
2. the herb’s high level of histidine production is found to be associated with an unusually low level of production of other amino acids
           
3. others of the closely related group of plants are also found to produce histidine in large quantities

4. cultivation of the herb in soil with high concentrations of the metals will, over an extended period, make the soil suitable for plants to which the metals are toxic
           
5. the concentration of histidine in the growing herb declines as the plant approaches maturity

大家看一下这道题目的答案是哪一个呢? 就是LZ考到的那道GWD

A

我選C  因為其他種類植物(跟此herb同樣生長在這高金屬含量土壤的植物) 也都測出了histidine  因此證明有histidine就能幫助植物生長於此類土壤

A只解釋了這個herb的各部位都有histidine  但不能證明她的存活就是因為histidine做的功

B指出兩種化學含量的消長 我也不認為就能證明histidine有效

我選C是因為這個選項明顯地提供了另一個佐證  這是我的想法  不知道對不對???

我要晕倒了!AB,C,D,E在讨论中都由人选啊,困惑中.....

肯定选C咯。..