You are presented with the question "What does a polar bear have to insulate its body?" and the following answer choices: 
- white
 - Cold blood
 - Less fat
 - Warm blood
 - environment
 - Bodily water
 - Extra fat
 - Animal fur

Now knowing that mammals have a layer of fat under the skin to help insulate the body and an extra layer of fat also helps protect the polar bear from the cold, choose the best answer.


 

       Extra fat  