The Chanterelle, a type of wild mushroom, grows beneath host trees such as the Douglas fir, which provide it with necessary sugars. The underground filaments of Chanterelles, which extract the sugars, in turn provide nutrients and water for their hosts. Because of this mutually beneficial realationship, harvesting the Chanterelles growing beneath a Douglas fir seriously endangers the tree.

Which of the following, if true, casts the most doubt on the conclusion drawn above?

A. the number of wild mushrooms harvested has increased in recent years

B. Chanterelles grow not only beneath Douglas firs but also beneath other host trees.

C. many types of wild mushrooms are found only in forests and cannot easily be grown elsewhere

D. the harvesting of wild mushrooms stimulates future growth of those mushrooms

E. yourng Douglas fir seedlings die without the nutrients and water provided by Chanterelle filaments

正确答案是D

题目的意思是：Douglas firs 可以给 Chanterelles 提供糖，而 Chanterelles 又可以给Douglas firs提供营养和水，他们是互利的。那题目中最后一句话为什么说将Chanterelles 种在Douglas firs下面会产生严重危险？不是应该是利于双方生长吗？

求解！D为什么正确

读原文：结论是说收割C会影响D树的生长，原因是两种植物的共生关系；问题问的是驳斥

A说野生蘑菇的数量近年来增长，无关项；

B说C不仅生长在D这个玩意下海生长在别的树下，无关项；

C说许多类型的野生蘑菇只在森林里找到，而且不容易生长在别处，也是无关项；

D说收割蘑菇会刺激这些蘑菇的生长，相关，因为原文说了收割C这种蘑菇，留着；

E说，年轻的D树的籽死亡，如果没有c提供的营养，原文提到了D树的生长，没说树籽怎么样，无关

我们最后再来看D；D说收割蘑菇会带来更多的蘑菇生长，这就意味着两种植物的共生关系依然存在，驳斥了结论