Answer
Natural selection operates on what is already existing, and it may find different pathways from the same basic ancestral structures. Many genes control development, and there are multiple ways to alter their expression and end up with a functional wing.
Work Step by Step
This question asks you to connect previous chapters dealing with evolution and the genetics of development with this material on muscles and skeletons. You should briefly review that earlier material, which includes sections on wing evolution in different vertebrates.