Which would you expect to be the most active on a cold day?

a chipmunk

a frog

a crocodile

a snake

A Chipmunk

Explanation:

The reptiles and amphibians are cold-blooded animals and their body temperature changes with the environmental temperature. The mammals and birds are warm-blooded animals and maintain constant body temperature. Therefore, the reptiles and amphibians go for hibernation during winter. But reptiles do brumation which is like the hibernation and the reptiles do not sleep in the entire winter. They reduce their metabolism and lie in the less active stage. Chipmunk is a mammal and cold-blooded animal. It does not go for hibernation and active during the day time in cold days. Sometimes chipmunks live in the colder region go for hibernation to escape it from cold but active during the day to keep it warm.

A chipmunk, because it is a mammal and is warm-blooded. The other three animals are not mammals, and their body temperatures depend on their external environment.