Critical Reasoning

Which of me following best completes the passage
below?
Adding ethanol to the gasoline used in cars reduces
exhaust emissions while slightly increasing
evaporation from gasoline tanks in cars and service
stations. These evaporative emissions are a major
component of the smog found in many large cities
in the hot summer months but, except in hot
weather, evaporative emissions pose less of a
pollution problem than exhaust emissions do.
Therefore, if air pollution were the only
consideration, one could conclude that -----.
(A) ethanol should be added only to gasoline
intended for use in large cities
(B) the benefits of using gasoline to which ethanol
has been added are greater in hot weather than
in cold weather
(C) the disadvantages of adding ethanol to gasoline
are likely to be outweighed by the advantages,
at least in cold weather
(D) it is not necessary to work at reducing exhaust
emissions in large cities
(E) adding ethanol to the gasoline used in large
cities will improve air quality in the cities in
hot weather