Sue: Commercial flights currently contribute more carbon dioxide to the atmosphere in one year than does the whole of Africa. If we want to reduce global warming we need to restrict the number of flights we take.

Dave: Did you know that by taking one inter-continental flight you cause more pollution than you would in twelve months of car travel?

Dave�s response to Sue�s comment serves to

A. reinforce Sue�s contention that flights are a major contributor to increased carbon dioxide levels
B. add more weight to her contention that we should reduce the number of flights we take
C. mitigate the force of her argument by suggesting that there is an alternative approach
D. suggest an alternative that will reduce the effect of pollution
E. question whether she really understands the severity of global warming