A. More of the cars in Donia’s capital city were made before 1993 than after 1993---Good incorrect choice. But we are still told that there are comparatively high no. of new cars, therefore a significant drop should have been there
B. The number of new cars sold per year in Donia has declined slightly since 1993-----weakens. If it has declined only slightly then a significant decline in emissions should have been seen.
C. Pollutants other than nitrogen dioxide that are emitted by automobiles have also been significantly reduced in Donia since 1993.---------out of scope
D. Many Donians who own cars made before 1993 have had catalytic converters installed in their cars. Does not explain the contrast
E. Most car trips in Donia’s capital city are too short for the catalytic converter to reach its effective working temperature------CORRECT