Critical Reasoning

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.

A. Automobile emissions are the largest single source of air pollution.
Incorrect : This does not support the experts' contention that 50% tax on new autos would not have any effect on air quality problem. Eliminated.

B. Some of the proceeds from the new tax would go toward expanding the nonpolluting commuter rail system.
Incorrect : Rail system is irrelevant to the scope of the argument.

C. Currently, the sales tax on new automobiles is considerably lower than 50 percent.
Incorrect : How does this affect the expert's contention about air quality problem? Ruled out.

D. Automobiles become less fuel efficient and therefore contribute more to air pollution as they age.
Correct : This supports the experts contention that increased tax on new autos will not have any effect on air quality problem because old autos contribute more to air pollution as they age.

E. The scrapping of automobiles causes insignificant amounts of air pollution.
Incorrect : Scrapping of autos is irrelevant to the scope of the argument.

IMO - D

This would support the experts contention about how the proposed tax on 'new automobiles' will not help to slow the deterioration of air quality since it's the older automobiles which are contributing to most of the pollution.