You are presented with the question "What kind of fuel use adds the most to global warming?" and the following answer choices: 
- elbow grease
 - vehicles
 - fossil
 - Pollution
 - engines
 - Cars
 - hydroelectricity
 - solar energy

Now knowing that burning fossil fuels increases the carbon in the atmosphere and global warming is caused by carbon dioxide trapped in the atmosphere, choose the best answer.


 

   fossil      