单选题 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 relationship, 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 alto 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、 (E) Young Douglas fir seedlings die without the nutrients and water provided by Chanterelle filaments.

【正确答案】 D

【答案解析】[解析] 本题问题目的是让我们反对结论，因此可用结论中的关键词“harvesting the Chanterelles”即“harvesting the wild mushroom”来定位选项，发现(A)、(D)有此关键词。如果对野生蘑菇的采割激发了这些蘑菇未来的生长，正如(D)所说，那么说明采割这些蘑菇并不会给那些树木造成伤害，因此起到了反对作用，所以(D)正确；而(A)只说明近年来蘑菇采割数量在增加，但没有说明采割以后怎么样，所以对结论不能起到任何作用。