Fact 1: Mammals have a layer of fat under the skin to help insulate the body.

Fact 2: Blubber, the fat of the whale, was once much sought after.

Given the two facts above, answer the question "What insulates?" with the following options: 
- with their fur
 - swamp vegetation
 - copper wire
 - Blankets
 - whale blubber
 - Animal fur
 - steel
 - aluminum foil


 

     whale blubber    