Fact 1: Head hair is especially important in preventing heat loss from the body.

Fact 2: Insulation serves to both prevent heat loss in the winter and heat gain in the summer.

Given the two facts above, answer the question "What is a form of natural insulation that humans have?" with the following options: 
- fur and fat
 - Fire
 - Blankets
 - Animal fur
 - Head hair
 - layers of fat
 - Clothes
 - copper


 

     Head hair    