I chose E just for one reason i.e. parallelism.
No other choice has correct parallelism.
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.
Here we are comparing the vehicles which are powered by natural gas. Now, lets look at the choices:
(A) less of certain pollutants
than the burning of gasoline or diesel fuel
Vehicles can not be compared with burning of fuel.
(B) fewer of certain pollutants
than burning gasoline or diesel fuel do -
Again vehicles are compared with burning
(C) less of certain pollutants
than gasoline or diesel fuel -
Vehicles getting compared with gasoline
(D) fewer of certain pollutants
than does burning gasoline or diesel fuel -
Again vehicle getting compared with burning
(E) less of certain pollutants
than those burning gasoline or diesel fuelThis sounds good. Vehicles are getting compared with other vehicles which burn gasoline
So this is the correct answer