You are presented with the question "What is used for generating heat by burning?" and the following answer choices: 
- Calcium carbonate
 - carbon dioxide
 - fossil fuels
 - clouds
 - peachleaf willow
 - space
 - calcite
 - sunlight

Now knowing that coal is used for generating heat by burning and like coal, petroleum is a fossil fuel, choose the best answer.


 

   fossil fuels      