Answer: 4)The reproductive cycles of males and females are regulated by hormones.
Explanation: In males and females reproductive cycles, hormones play important roles. Among the hormones associated with reproduction are testosterone and androgen in males, oestrogen and progesterone in females. Testosterone stimulates the development of male secondary sexual characteristics such as deepening of voice, growth of beards, growth of pubic and axillary hair, enlargement of the penis and development of typical male physique. Oestrogen stimulates the development of female secondary characteristics such as enlargement of the breasts, development of typical female physique, voice pitch and hair pattern while progesterone stimulates the uterus and prepares it for pregnancy and induces milk secretion by the mammary glands.