Fact 1: Coal is used to produce electricity by burning in coal-fire power stations.

Fact 2: Heat is essential to the burning process.

Given the two facts above, answer the question "How does coal produce electricity?" with the following options: 
- It remains dormant
 - It gets cooled
 - By rubbing together
 - chemical reaction
 - It gets heated up
 - major threat to health
 - Through magnetism
 - heat energy


 

     It gets heated up    