The Use of Hydrogen Gas Would Eliminate Most of the Air

The use of hydrogen gas would eliminate most of the air pollution problems we have today because:

A) When it burns it combines with carbon dioxide and removes it from the air.
B) When it burns it combines with water to produce heavy rainwater.
C) When it burns it combines with oxygen gas in the air to produce water vapor.
D) When it burns it combines with carbon to produce methane gas.
E) None of these answers.