The principal sign of sexual maturity in males is

A) growth of the penis.
B) growth of testes.
C) ejaculation of semen.
D) the adolescent growth spurt.

The growth of testes is the principal sign of sexual maturity in males. Testes typically begin to grow at around age 10 or 11, and by age 14 they have usually reached their adult size. This growth is accompanied by an increase in testosterone production, which drives the remainder of male sexual development.

Answer: A, C
While the growth of testes is the primary sign of male sexual maturity, the growth of the penis and ejaculation of semen are also important markers of sexual development. These typically occur later than testicular growth, with penis growth often continuing into the late teenage years and ejaculation beginning around age 12-13. The adolescent growth spurt, while a sign of overall physical development, is not a direct marker of sexual maturity.