Final answer:
Puberty is the stage when individuals achieve sexual maturity, marked by primary and secondary sexual characteristics. Fertility milestones include menarche for females and spermarche for males.
Explanation:
Puberty is a period of rapid growth and sexual maturation during which individuals become sexually mature. This stage involves primary sexual characteristics like the growth of reproductive organs and secondary sexual characteristics that signify sexual maturity. For females, the achievement of fertility is marked by menarche, the first menstrual period, while males experience spermarche, the first ejaculation of semen.
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