Fact 1: High temperatures can cause an object to combust.

Fact 2: Incineration requires very high temperatures for efficient combustion.

Given the two facts above, answer the question "What causes an object to combust?" with the following options: 
- heating liquids
 - friction
 - It gets heated up
 - incineration
 - heat energy
 - flow of electrons
 - Electrical energy
 - Energy.


 

    incineration     