Catalytic converters题求解

GWD5-Q38:

Nitrogendioxide is a pollutant emitted by automobiles. Catalytic converters, devices designed to reduce nitrogen dioxideemissions, have been required in all new cars in Donia since 1993, and as aresult, nitrogen dioxide emissions have been significantly reduced throughoutmost of the country.  Yet although theproportion of new cars in Donia’scapital city has always been comparatively high, nitrogen dioxideemissions there have showed only an insignificant decline since 1993.

Whichof the following, if true, most helps to explain the insignificant decline innitrogen dioxide emissions in Donia’s capital city?

A.     More of the cars in Donia’s capital city were made before1993 than after 1993. 只能表示

B.     The number of new cars sold per year in Donia has declinedslightly since 1993.

C.     Pollutants other than nitrogen dioxide that are emitted byautomobiles have also been significantly reduced in Donia since 1993.

D.     Many Donians who own cars made before 1993 have hadcatalytic converters installed in their cars.

E.      Most car trips in Donia’s capital city are too short forthe catalytic converter to reach its effective working temperature.