The Hypothesis That Birds Evolved from Dinosaurs Is Potentially Confusing

The hypothesis that birds evolved from dinosaurs is potentially confusing because dinosaurs-at least the ones thought to be the ancestors of birds-did not fly. Why do biologists still hold to this hypothesis despite this point?

A) Dinosaurs may have used feathers to attract mates.
B) Feathers in dinosaurs are believed to have served as insulation.
C) Dinosaurs may have used feathers as an aggressive display to ward off enemies.
D) All of the above are supporting evidence for this hypothesis.