Question ID:PT65 S4 Q1 Passage:When a forest is subject to acid rain, the calcium level in the soil declines. Spruce, fir, and sugar maple trees all need calcium to survive. However, sugar maples in forests that receive significant acid rain are much more likely to show signs of decline consistent with calcium deficiency than are spruces or firs in such forests. Stem:Which one of the following, if true, most helps to explain the greater decline among sugar maples? Correct Answer Choice:CChoice A:Soil in which calcium levels are significantly diminished by acid rain is also likely to be damaged in other ways by acid rain. Choice B:Sugar maples that do not receive enough calcium deteriorate less rapidly than spruces or firs that do not receive enough calcium. Choice C:Spruces and firs, unlike sugar maples, can extract calcium from a mineral compound that is common in soil and is not affected by acid rain. Choice D:Sugar maples require more calcium in the spring and summer than they do in the fall and winter. Choice E:Unlike spruces or firs, most sugar maples are native to areas that receive a lot of acid rain.