Bats, butterflies, and most birds share flight as a trait. however, none of these organisms share the same class, this trait is most likely an example of what type of evolution?

The correct answer is convergent evolution.

Explanation:

The wings of bats, butterflies, and most birds are the example of analogous structure. Analogous structures are the structures which are similar in appearance and function but have separate evolutionary origin.

They are similar superficially because they experienced a natural selection that evolved them to have that shape which helps them to fly. Analogous structures are produced due to convergent evolution.  

Convergent evolution describes the presence of the same trait in unrelated species. Therefore the correct answer is convergent evolution.