The chanterelle, a type of wild mushroom, grows beneth host trees, such as the douglas fir, which provide it with necessary sugars. The underground filaments of chanterelles, which extract sugars, in turn provide nutrients and water for the hosts because of this mutual beneficial relationship, harvesting the chanterelles growing beneath a douglas fir sereiously endangers the tree. Which of the following, is true, casts the most doubt on the conclusion drawn above?
a. the number of wild mushrooms harvest as increased in recent years.
b. chantelles grow not only beneath douglas fir, but also beneath other host trees
c. many types f wild mushrooms are found only in forests & cannot easily be grown elsewhere
d. The harvesting of wildmushrooms stimulates future growth of those mushrooms.
e. young douglas fir seedings die without the nutrients & watere provided by chanterlle filaments.
請教各位 ,正確答案是 D