an insect that lives and feeds on the body of an alligator an ant that lives on a plant and defends the plant from other insects a bird that migrates to follow the movements of the butterflies that it eats a deer that eats one kind of plant, which allows another kind of plant to grow in its place
I gave my students this multiple choice question: Which relationship is mutualistic?

Only one answer is correct among these 4 choices:
- an insect that lives and feeds on the body of an alligator
- an ant that lives on a plant and defends the plant from other insects
- a bird that migrates to follow the movements of the butterflies that it eats
- a deer that eats one kind of plant, which allows another kind of plant to grow in its place

Could you tell me which one is correct?

an ant that lives on a plant and defends the plant from other insects