What is considered a primary sexual characteristic in males?

The development of male reproductive organs is classified as a primary sexual characteristic in males because these characteristics are directly involved in reproduction and are present at birth or become prominent during puberty due to hormonal changes. Primary sexual characteristics are the structures that are necessary for reproduction, such as the testes and penis in males, which develop and mature during puberty.

Other changes, such as facial hair development, increased muscle mass, and voice deepening, are considered secondary sexual characteristics. These traits are not directly involved in reproductive functions but are associated with the male phenotype and arise from additional hormonal influences during puberty.