PREP1-56 还没有人问过，如何排除A，谢谢！

56.   (34605-!-item-!-188;#058&007579)

Crops can be traded on the futures market before they are harvested.  If a poor corn harvest is predicted, prices of corn futures rise; if a bountiful corn harvest is predicted, prices of corn futures fall.  This morning meteorologists are predicting much-needed rain for the corn-growing region starting tomorrow.  Therefore, since adequate moisture is essential for the current crop's survival, prices of corn futures will fall sharply today.

Which of the following, if true, most weakens the argument above?

(A) Corn that does not receive adequate moisture during its critical pollination stage will not produce a bountiful harvest.

(B) Futures prices for corn have been fluctuating more dramatically this season than last season.

(C) The rain that meteorologists predicted for tomorrow is expected to extend well beyond the corn-growing region.

(D) Agriculture experts announced today that a disease that has devastated some of the corn crop will spread widely before the end of the growing season.

(E) Most people who trade in corn futures rarely take physical possession of the corn they trade.

答案D，虽然我也选了D，但A为什么不对呢？感觉A也是削弱。

请NN指点，谢谢！

说说我当时想A的思路：在pollination stage的时候，没有充足的雨水，即使明天开始（不是指pollination stage）有充足的雨水了，产量也未必提高。所以削弱。即他因削弱。他因是：这些corn在pollination stage没有充足的雨水。

但D比A更直接。

自己问题，自己理解。。。。不确定对否，to discuss。

削弱题

他因削弱

结论：潮气有利于粮食存活----粮食产量上升（背景的推理信息）---粮食价格下降
            （因果）

D：
            病虫害—粮食产量下降—粮食价格上升（与结论相反，所以削弱）