Fact 1: Coal is used for generating heat by burning.

Fact 2: Like coal, petroleum is a fossil fuel.

Given the two facts above, answer the question "What is used for generating heat by burning?" with the following options: 
- Calcium carbonate
 - carbon dioxide
 - fossil fuels
 - clouds
 - peachleaf willow
 - space
 - calcite
 - sunlight


 

   fossil fuels      