You are presented with the question "Mammals can also generate little bursts of heat by" and the following answer choices: 
- muscle contractions
 - circulation
 - exhalation
 - Temperature changing
 - Movement of an air mass
 - flow of electrons
 - vibrations
 - with their fur

Now knowing that mammals can also generate little bursts of heat by shivering and shivering causes muscle contractions to warm the body, choose the best answer.


 

 muscle contractions        