Secondary sexual characters appear in
(a) fetus
(b) childhood
(c) pubery
(d) adulthood
(c) puberty
External accessory or secondary sexual characters are the changes that occur in males and females during puberty due to the high level of male and female hormones i.e., testosterone in males and estrogen in females. The examples of secondary characters are the growth of beards, mustaches in males, growth of breasts, broadening of the pelvis, etc in females.
So, the correct option is C.