38. Amphibianpopulations are declining in numbers worldwide. Not coincidentally, the earth’sozone layer has been continuously depleted throughout the last 50 years.Atmospheric ozone blocks UV-B, a type of ultraviolet radiation that iscontinuously produced by the sun, and which can damage genes. Becauseamphibians lack hair, hide, or feathers to shield them, they are particularlyvulnerable to UV-B radiation. In addition, their gelatinous eggs lack theprotection of leathery or hard shells. Thus, the primary cause of the decliningamphibian population is the depletion of the ozone layer.
Each of thefollowing, if true, would strengthen the argument EXCEPT:
A. Of the various types ofradiation blocked by atmospheric ozone, UV-B is the only type that can damagegenes.
B. Amphibian populations aredeclining far more rapidly than are the populations of non-amphibian specieswhose tissues and eggs have more natural protection from UV-B.
C. Atmospheric ozone has beensignificantly depleted above all the areas of the world in which amphibianpopulations are declining.
D. The natural habitat ofamphibians has not become smaller over the past century.
E. Amphibian populations havedeclined continuously for the last 50 years.
答案是D 我认为是A
关键结论是: depletion of the ozone layer -> decliningamphibian population 而不是 UV-B->decliningamphibian population
所以A中，即使UV-B是one of the types that can damage genes 也没有错啊。
D说1个世纪以来一直没有下降，那就是一种支持，是50年来的depletion of the ozone layer导致的，而不是别的什么原因。
