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 ______.
- histidine is found in all parts of the plant—roots, stem, leaves, and flowers
- the herb’s high level of histidine production is found to be associated with an unusually low level of production of other amino acids
- others of the closely related group of plants are also found to produce histidine in large quantities
- 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
- the concentration of histidine in the growing herb declines as the plant approaches maturity
这道题我用GWD28-Q28搜索几乎没有得到肯定的答复，所以还是想把它拿出来问问。以下是我自己的想法，欢迎拍。
本题最后总结论：histidine的产生导致植物能在含有毒金属的土壤中生存，论据是此酸将金属转化无毒。
A。只说了histidine 本身的性质，和结论无关
B。也只说了histidine 本身的性质，和结论无关
C。很有争议。个人认为这个选项还是有点问题。
问题1、one of a group of closely related plants 是什么意思？这个herb是这个group中的一个，还是说这个herb是这个group的集合？
问题2、从C选项others of the closely related group of plants 感觉herb是一个group，这个选项讲出了这个herb以外其他植物也具备这个特点，但是这可以说是前提的完全重复，并没有从新的方面起到对结论的支持作用。
D。应该是张冠李戴，结论讨论histidine和土壤和生存的关系，这个选项说因为cultivate使得突然无毒。
E。个人是这样解释，在herb接近成熟期，这个酸的量就减少了，结合前提在生长期曾经产生大量的酸。说明这个酸是随着生长而变化的。刚生长的时候土壤毒性大，因此产生较多的酸解毒，快到成熟期基本毒都已已经转化的差不多了，因此酸的量就减少了，成正态分布。
不知道我的解释是否合理。还请牛牛评论。这道题我第一遍没有做出来，第二遍时候直接选的E，本人并不是根据答案反推。 | 
