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

Fact 2: Dead vegetation settles and becomes peat, a precursor of coal.

Given the two facts above, answer the question "What becomes something that is burned to generate heat?" with the following options: 
- glass
 - dead vegetation
 - Fuel cells
 - preserved vegetation
 - Electrical energy
 - hydrogen and oxygen
 - clouds
 - electricity


 

  dead vegetation       