You are presented with the question "Why do some animals have hair that grows longer during the winter?" and the following answer choices: 
- It expands
 - to make braids
 - to wear a scarf
 - to attract mates
 - When it's cold
 - to stay warm
 - It remains dormant
 - genetic diversity

Now knowing that some animals' fur grows thicker for staying warm in the winter and mammals have hair and fur, choose the best answer.


 

      to stay warm   