Fact 1: Using a gasoline engine requires burning gasoline.

Fact 2: Fossil fuels include coal, oil, natural gas, and gasoline.

Given the two facts above, answer the question "What does an engine require burning?" with the following options: 
- Time and energy
 - energy
 - wind
 - water
 - carbon dioxide
 - layers of fat
 - fossil fuels
 - sunlight


 

       fossil fuels  