You are presented with the question "what happens when many muscles contract a little bit all at once?" and the following answer choices: 
- heat is produced
 - To keep their body heat.
 - biceps
 - sweating
 - digestion
 - rapid expansion
 - preventing heat transfer
 - death

Now knowing that shivering occurs when many muscles contract a little bit all at once and heat production is increased by shivering and non-shivering thermogenesis , choose the best answer.


 

 heat is produced        