Fact 1: Hibernation is used for conserving energy by some animals. Fact 2: Animals that sleep through the winter are said to hibernate. Given the two facts above, why do animals sleep through winter?
Options:
i. To conserve energy;
ii. recovery time from fatigue;
iii. They get bored;
iv. Endocrine system;
v. They only like warmth;
vi. dormant state;
vii. To save time;
viii. hydration;
i.