Which of the following most logically completes the argument below?
Using broad-spectrum weed killers on weeds that are competing with crops for sunlight, water, and nutrients presents a difficulty: how to keep the crop from being killed along with the weeds. For at least some food crops, specially treated seed that produces plants resistant to weed killers is under development. This resistance wears off as the plants mature. Therefore, the special seed treatment will be especially useful for plants that ______.
我是这么做题的 A里面的summer squash和E里面的leaves or roots太突兀了,提干都没出现过,没办法用来做比较以支持原文,不选 B首先我觉得easy to treat individually中的individually很奇怪,其次as ... and beans do中的beans也很突兀,不选 D为什么要提single crop? 至于C,原文提到the resistance会随着plant mature而减弱,所以C里面的as they approach maturity,shade dense enough to keep weeds from growing是对的