What is the contrapositive of the following conditional statement?

"If a bird is an ostrich, then it cannot fly."

If a bird can fly, then it is not an ostrich.
If a bird is not an ostrich, then it can fly.
If a bird cannot fly, then it is an ostrich.
If a bird is an ostrich, then it cannot fly.

If a bird can fly, then it is not an ostrich.