Fact 1: Shivering occurs when many muscles contract a little bit all at once.

Fact 2: Shivering causes muscle contractions to warm the body.

Given the two facts above, answer the question "What does shivering generate?" with the following options: 
- kinetic
 - energy
 - friction
 - Energy.
 - expels heat
 - heat
 - warmth
 - rhythm


 

       warmth  