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 non-amphibian 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.
答案是A，我觉得应该是D吧？
D是排除它因，所以对的。
A，取非。假设还有其他物质也能伤害基因，同时这些物质也能被臭氧阻挡。因为臭氧减少了，所也阻挡物质的作用便弱，所以这些物质就跑到地球上伤害基因，这也能说明这个物种减少是因为臭氧减少。所以取非后对结论还有支持作用。所以A错
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