请问一道费费题38

Rocli

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.
我觉得选D呀

Rocli

understand,thanks a lot

zyh79

结论： amphibian数量下降是由于臭氧层的消失。
假设： amphibian的居住地并未减少。排除了居住地减少导致amphibian数量下降的可能性
A答案只说 UV-B 是唯一杀死基因的射线，与结论无关，多种射线也可以。
除非结论是： amphibian数量下降是由于UV-B

Rocli

D怎么是假设条件之一呀,答案为什么是A呀

tongxun

D 是其中结论成立的假设条件之一。怎能weaken？