Lanugo is the thin, soft and unpigmented hair present in the
fetus or newborn.
Vellus is the short, thin, light pigmented, fine hair that
replaces the lanugo in the childhood.
Terminal hair is the thick, dark pigmented hair that appears
during and after puberty. Usually it present on scalp, pubis, arm
pit etc. It replaces the vellus hair.
Keratin is the protein substance that makes the hair, nails,
feathers (in birds), claws ( in animals).
So the
Answer is Keratin.
