Which hormone is primarily responsible for the development of secondary sexual characteristics in males?

Testosterone is the hormone primarily responsible for the development of secondary sexual characteristics in males. During puberty, an increase in testosterone levels leads to several key changes, including the growth of facial and body hair, deepening of the voice, and increased muscle mass. These traits are indicative of male physical development and differentiation, contributing to what is referred to as secondary sexual characteristics.

Testosterone is produced primarily in the testes and has a critical role not only in the development of physical traits but also in regulating other functions, such as libido and sperm production. Its effects are mediated through androgen receptors in various tissues, which leads to the expression of genes involved in the characteristics mentioned.

The other hormones listed, like progesterone, luteinizing hormone, and follicle-stimulating hormone, have different roles; for instance, progesterone is more associated with female reproductive processes. Luteinizing hormone and follicle-stimulating hormone are involved in the regulation of testosterone production and sperm development, respectively, but they do not directly cause the development of secondary sexual characteristics as testosterone does.