After trauma a tooth become yellowish in color, this is due to.. Pulp is partially or completely obliterated

After trauma a tooth become yellowish in color, this is due to:
a. Necrotic pulp.
b. Irreversible pulpitis.
c. Pulp is partially or completely obliterated.***
d. Hemorrhage in the pulp.
Endo Principles and Practice of Endodontics WALTON – page 45 yellowish discoloration of the crown is often a Manifestation of calcific metamorphosis.