Fact 1: Using a car causes pollution.

Fact 2: Pollution is a damaging excess of contaminants.

Given the two facts above, answer the question "How do cars damage the environment?" with the following options: 
- Battery useage
 - exposure to the sun
 - Emitting an excess of contaminants
 - they travel great distances
 - Using too much gas
 - Causing accidents
 - depress neuronal excitability
 - within and around


 

   Emitting an excess of contaminants      