对费费38题A选项的不解，请指点

Another way to interprete the answer.

Assume A is not correct, then there are some other radiation will damage Amphibian's gene. Thefore, the depletion of ozone will create more UV-B and other radiations. And hence, the Amphibian population will decline faster. Hereafter, the decline of Amphibian population is still because of the depletion of ozone. It does not weaken the original conclusion. Therefore, A is not the answer. In this counter-deduction process, you can see whether UV-B is the only type of radiation, which can damage genes, is irrelevant to the original conclusion.

Proof that D is wrong:

Assume D is wrong. Then the shrink of Amphibian's habitat could lead to its population decline, which weaken the original conclusion. Therefore, D strengthen the conclusion and should not be the answer.

5楼的很牛呀！

我想了半天没想出来，看了5楼的才明白点。

A可以理解为不是加强，反倒是削弱结论！因为如果UV-B不是唯一可以破坏基因的射线，那么臭氧层的作用就会更大（不但阻止了UV-B还阻止了其他可以破坏基因的射线），所以有了唯一性，臭氧层的作用反倒给减小了！

旧版的费费该题答案为A。

1。D是错的：因为D提出一个amphibian population 减少的它因

2。原文推理：amphibian population 减少，同时臭氧层也减少，臭氧层能阻挡UV-B，UV-B会DAMAGE基因。所以（结论），臭氧层的减少是amphibian population 减少的原因。

3。A不是必要条件。将A取非后，在臭氧层阻挡的射线中，UV-B不是唯一一种能DAMAGE基因的。也就是还有其他也能DANANGE基因。其他射线也能DAMAGE基因这个结果并不能使结论不成立。同时A（UV-B是唯一能DAMAGE基因的）也没有通过加强证据或排除它因等形式加强结论。

4。其他选项都是通过证明证据或排除它因的方式支持结论。