According to the theory of evolution, birds' feathers evolved from.
a. reptile scales
b. gill slits.
c. fish fins.
d. gill arches.

According to the theory of evolution, birds' feathers evolved from "reptile scales"--specifically those of dinosaurs, since these became increasingly valuable over very small arms. 

According to the study of evolution, the evolution of the bird’s feathers came from the reptile scales. They explain the theory of evolution of the bird’s feathers from the scales of the dinosaurs that lived a very long time ago. They showed the evolution like this:
The Crocodilians à The Archosauria à The Dinosauria à The Saurischia à The Therapoda à The  Coelurosauria à The Maniraptora à Aves à Birds . This is how they believed birds feathers were evolved in the present.

Yes it is hereditary because of the penis