You are presented with the question "which can help warm-blooded animals stay active in cold?" and the following answer choices: 
- shivering
 - four limbs
 - Animal fur
 - sleep
 - sweating
 - hibernation
 - cold blood
 - fur seals

Now knowing that mammals can also generate little bursts of heat by shivering and most mammals can be active even in cold weather because they are warm-blooded, choose the best answer.


 

 shivering        