You are presented with the question "what does muscles contracting a little bit all at once do?" and the following answer choices: 
- biceps
 - cause death
 - respiration
 - staying warm
 - rapid expansion
 - movement
 - heat the body
 - to move people

Now knowing that shivering occurs when many muscles contract a little bit all at once and shivering heats the body, choose the best answer.


 

       heat the body  