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

Fact 2: Shivering provides heat generated by muscle contraction.

Given the two facts above, answer the question "What does muscles contracting provide?" with the following options: 
- strong
 - Cold
 - warmth
 - Energy
 - Injury
 - Oxygen
 - forces
 - Heat


 

        Heat 