Hibernation is used for conserving energy by some animals, and animals that sleep through the winter are said to hibernate. Given these facts, why do animals sleep through winter among the following options:
- To conserve energy
 - recovery time from fatigue
 - They get bored
 - Endocrine system
 - They only like warmth
 - dormant state
 - To save time
 - hydration


 

 To conserve energy        