我选C, 因为去解释现象的hypothesis为: the herb’s high histidine production is what allows it to grow in metal-rich soils. 证据是histidine renders these toxic metals chemically inert.所以argument 说histidian production 是使A certain cultivated herb of one of a group of closely related plants 能够grow的原因. C 说明了, 这个hypothesis没有以偏盖全. 如果别的closely related plants也是因为这个原因而growth in toxic soil. 这个hypothesis因此得到support. D 我认为是无关选项, 尤其说到over an exdended period, 原文没有说histidine 只能暂时让plants survive. 忘进一步讨论 |