求教一个逻辑题,急急急啊!

Since the passage of the state’s Clean Air Act ten years ago, the level of industrial pollutants in the air has fallen by an average of 18 percent. This suggests that the restrictions on industry embodied in the act have worked effectively. However, during the same period the state has also suffered through a period of economic decline. The number of businesses in the state has fallen by 10 percent, and the number of workers employed has fallen by 12 percent. It is probable that the business decline, rather than the regulations in the act, is responsible for at least half of the decline in the pollution

        Which of the following, if true, would most seriously weaken the conclusion drawn in the passage above?

        (A) During the last ten years, economic conditions in the nation as a whole have been worse than those within the state.

(B) Amendments to the Clean Air Act that were enacted six years ago have substantially strengthened its restrictions on industrial air pollution.

(C) Of the businesses that ceased operating in the state during the last ten years, only 5 percent were engaged in air-polluting industries.

(D) Several large corporations left the state during the last ten years partly in order to avoid compliance with the Clean Air Act.

(E) Due to its small budget, the state office charged with enforcement of the Clean Air Act has prosecuted only two violators of the law since its passage

请问B和C怎么选啊?好象两个都有道理的嘛

B选项只是加强了条件，并没有提到污染下降

与原结论无关啊

可是C的话存在一种可能就是这5%停业的企业对污染要负大部分的责任,这样的话这5%企业的退出对整个环境的改善不是起到很大的作用了吗?所以我觉得5%这个数据不能说明企业对污染的影响很小.所以我觉得答案C有问题!

我有点明白出题人的意思.是说only 5% 表明 企业对污染的影响不大,因此停不停对污染的减少没什么作用的,这样就削弱了结论,因为结论说business decline is responsible for the pollution decline,总觉得weaken 的不是很有力啊

文章的意思是： business decline比之the regulations in the act在减少污染排放上更加有效咯

找weaken就是找business decline相对无效

C：相对无效，因为business decline只造成了5％的排污企业倒闭，不能从根本上解释为什么business decline会更加有效的促成了排放减少。

B：6年前法律修正，持续加强了对工业污染的限制。但是否能造成法律比之business decline能使得污染排放减少显得更加有效？疑问。。。。。。因为之前也有法律啊，且也同样限制排放