求助GWD上的一道逻辑题~

哈菲

Certain politicians in the country of Birangi argue that a 50 percent tax on new automobiles would halt the rapid increase of automobiles on Birangi’s roads and thereby slow the deterioration of Birangi’s air quality.  Although most experts agree that such a tax would result in fewer Birangians buying new vehicles and gradually reduce the number of automobiles on Birangi’s roads, they contend that it would have little impact on Birangi’s air-quality problem.

Which of the following, if true in Birangi, would most strongly support the experts’ contention about the effect of the proposed automobile tax on Birangi’s air-quality problem?

A.      Automobile emissions are the largest single source of air pollution.

B.      Some of the proceeds from the new tax would go toward expanding the nonpolluting commuter rail system.

C.      Currently, the sales tax on new automobiles is considerably lower than 50 percent.

D.      ！Automobiles become less fuel efficient and therefore contribute more to air pollution as they age.

E.       The scrapping of automobiles causes insignificant amounts of air pollution.

 为什么不是A呢，麻烦大家帮忙解答一下吧！

isaxi

某人说加50％税可以减少新汽车购买，从而提高空气质量。专家说提高税可以减少新汽车，但是不能提高空气质量。问：下面哪个选项支持专家的意见。
A 汽车排放是空气污染的最大单一源。
这道题问的是减少新汽车购买是否能提高空气质量，A和讨论的内容无关。
D 汽车用久了会有更大的污染。
新汽车减少了，所以老汽车就用得更久，从而不是减少污染，而是增加污染。