白勇书上面的一题(疑惑)

164.Because natural gas is composed mostly of methane, a simple hydrocarbon, vehicles powered by natural gas emit less of certain pollutants than the burning of gasoline or diesel fuel.
(A) less of certain pollutants than the burning of gasoline or diesel fuel
(B) fewer of certain pollutants than burning gasoline or diesel fuel do
(C) less of certain pollutants than gasoline or diesel fuel
(D) fewer of certain pollutants than does burning gasoline or diesel fuel
(E) less of certain pollutants than those burning gasoline or diesel fuel

答案是E, 可是我觉得E中没有动词, 应该补上一个do, 所以这道题好像没有正确答案

b比e更好一点,  b中缺vehicles, 而vehicles是重复主语，应该可以省略，不知道大家怎么看待这个问题

fewer 通常修饰人，less 即可修饰不可数也可修饰可数名词。e 选项确实是省略了do

在我看来，do确实不该省略，不过此题其他选项错误也很明显。此题 e 选项those前加上do应该是最正确的。但如果仅做题而言，也只能选 e.

等待牛牛解答。