Answer:
(E) a,b, and c
Explanation:
Flightlessness birds are distant, so this feature appeared different times in the phylogenic tree of the birds. This means, that this trait is not synapomorphic. It is a result of convergent evolution in these species (penguins, ostriches, flightless ducks, and rails), probably as a consequence of similar environmental pressures or advantages. Also, it is a homoplasic trait because this feature has not a recent common ancestor to these species. Finally, it is an evolutionary reversal too because it is a trait that bird's ancestors had, but not the most immediate ancestor of these birds.