38. Amphibian populations are declining in numbers worldwide. Not coincidentally, the earth’s ozone layer has been continuously depleted throughout the last 50 years. Atmospheric ozone blocks UV-B, a type of ultraviolet radiation that is continuously produced by the sun, and which can damage genes. Because amphibians lack hair, hide, or feathers to shield them, they are particularly vulnerable to UV-B radiation. In addition, their gelatinous eggs lack the protection of leathery or hard shells. Thus, the primary cause of the declining amphibian population is the depletion of the ozone layer. Each of the following, if true, would strengthen the argument EXCEPT: (A) Of the various types of radiation blocked by atmospheric ozone, UV-B is the only type that can damage genes. (B) Amphibian populations are declining far more rapidly than are the populations of nonamphibian species whose tissues and eggs have more natural protection from UV-B. (C) Atmospheric ozone has been significantly depleted above all the areas of the world in which amphibian populations are declining. (D) The natural habitat of amphibians has not become smaller over the past century. (E) Amphibian populations have declined continuously for the last 50 years. 我做题时直觉选了A。题目版的费费135提供的答案也是A。但是，在详解版的费费135中，答案是D。 详解版的解释是： A：支持说明为什么是UV-B而不是其他原因。
B：支持说明为什么UV-B会降低两栖动物的数量。
C：提供空间论据说明臭氧层受损和两栖动物数量减少的相关性。
D：中性评价。不Weaken也不Strengthen. E：提供时间论据说明臭氧层受损和两栖动物数量减少的相关性。
但是我不是很理解。我的思路是：A）UV-B is the only type that can damage genes.强调only对原文并没有帮助。原文已经说了UV-B是导致两栖动物数量减少的原因（通过伤害基因），所以再说一遍（即使强调了唯一）也没有加强结论。
D）两栖动物栖息地的减少有可能导致两栖动物的减少，现在排除他因，起到加强结论的作用。
请哪位牛人帮忙答疑解惑，谢谢！ | 
