Final answer:
The secondary sex characteristic listed is C. increase in perspiration, which emerges due to hormonal changes during puberty.
Step-by-step explanation:
The secondary sex characteristic among the options provided is C. increase in perspiration. Secondary sex characteristics are physical traits that are not directly involved in reproduction but emerge during puberty as a result of increasing levels of sex hormones such as testosterone and estrogen. Apart from an increase in perspiration, these characteristics include the development of facial, axillary, and pubic hair, a deepening of the voice in males, and the growth of breasts in females. Reproductive maturity (A) and sperm production (B) are primary sex characteristics, whereas an increase in height (D) is more generally associated with the overall growth during puberty rather than secondary sexual development.