The correct answer should be D.) Declines in poisonous, non-edible mushroom species in cool climates. Although question B does provide evidence that Global warming could be the cause of the declines, it still doesn't disprove the theory that overharvesting could be the cause as well. Question C could be caused by a number of things, such as deforestation, a local change in climate, removal of agricultural pests, ect. Question A supports the hypothesis that overharvesting is the cause of the decline, instead of disproving it. Hope this helped!