Potato cyst nematodes are a pest of potato crops. The nematodes can lie dormant for several years in their cysts, which are protective capsules, and do not emerge except in the presence of chemicals emitted by potato roots. A company that has identified the relevant chemicals is planning to market them to potato farmers to spread on their fields when no potatoes are planted; any nematodes that emerge will soon starve to death.
Which of the following, if true, best supports the claim that the company’s plan will be successful?
(A) Nematodes that have emerged from their cysts can be killed by ordinary pesticides.
(B) The only part of a potato plant that a nematode eats is the roots.
(C) Some bacteria commonly present in the roots of potatoes digest the chemicals that cause the nematodes to emerge from their cysts.
(D) Trials have shown that spreading even minute quantities of the chemicals on potato fields caused nine-tenths of the nematodes present to emerge from their cysts.
(E) The chemicals that cause the nematodes to emerge from their cysts are not emitted all the time the potato plant is growing.
answer D
我的疑問在於D為什麼可以support
因為D的效果不是已經被題幹證實了嗎
再重複說一次chemical的作用豈不是多此一舉
更何況D也沒有因果關係告知害蟲會因此而餓死
相形之下 B可能還比較有說服力
起碼他說明害蟲只吃馬鈴薯的根
即使題目未說明是否害蟲的食物來源只能靠馬鈴薯的根
但起碼也有讓食物來源減少造成害蟲餓肚子的效果
請各位大牛指點迷津~~~