Fact 1: Some animals' fur grows thicker for staying warm in the winter. Fact 2: Mammals have hair and fur. Given the two facts above, why do some animals have hair that grows longer during the winter?

Choose your answer from:
(A). It expands.
(B). to make braids.
(C). to wear a scarf.
(D). to attract mates.
(E). When it's cold.
(F). to stay warm.
(G). It remains dormant.
(H). genetic diversity.
The answer is:
(F).