<span>Selection (a) is the best answer. Rainforests, through their ecosystems, are able to mitigate the effects of prolonged rain events and droughts that could take place in the areas in which they reside. The expansive canopies and tall trees hold in the moisture that does fall to make sure that the areas within them receive sufficient moisture for growth.</span>
More hydrothermal resources exist in the Western regions of the United States because lack of groundwater and extended drought has reduced the number of vents.