mba1382 wrote:
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 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) Young Douglas fir seedlings die without the nutrients and water provided by chanterelle filaments
Please explain your reasoning for the answers provided.
Thanks.
What is the conclusion?
"harvesting the mushroom seriously endangers these trees"
To weaken it we need to provide an explanation why harvesting the mushroom may not endanger these trees.
We know that mushrooms and trees benefit each other.
Option (D) tells us that harvesting of wild mushrooms stimulates future growth of those mushrooms. This means that even if you harvest the mushrooms, they will grow back and hence the beneficial relation will continue or perhaps even become better since harvesting stimulates future growth.
This weakens the statement that harvesting the mushrooms endangers these trees.
None of the other options weaken our conclusion.