Select the vertebrate.

 - red-spotted purple butterfly
 - bess beetle
 - domestic cat
 - earthworm
A bess beetle is an insect. Like other insects, a bess beetle is an invertebrate. It does not have a backbone. It has an exoskeleton.
A domestic cat is a mammal. Like other mammals, a domestic cat is a vertebrate. It has a backbone.
An earthworm is a worm. Like other worms, an earthworm is an invertebrate. It does not have a backbone. It has a soft body.
A red-spotted purple butterfly is an insect. Like other insects, a red-spotted purple butterfly is an invertebrate. It does not have a backbone. It has an exoskeleton.