Which statement provides the best argument for why bird and butterfly wings evolved to have a similar function but differ in structure?

a
This is an example of embryological structures, which indicates that bird and butterfly wings have similar function because they develop in much the same way.
b
This is an example of homologous structures, which indicates that they share a common evolutionary origin.
c
This is an example of vestigial structures, which indicates that the common ancestor of birds and butterflies had the same structure as birds.
d
This is an example of analogous structures, which indicates that they are not closely related even though they perform the same function.

b

This is an example of homologous structures, which indicates that they share a common evolutionary origin. This argument suggests that bird and butterfly wings evolved to have a similar function but differ in structure because they both evolved from a common ancestor that had a similar limb structure that was then modified in different ways over time.