Final answer:
The primary sex organs are the gonads; testis in males and ovaries in females, which are essential for reproduction and hormone production.
Step-by-step explanation:
The primary sex organs, also known as gonads, are essential for reproductive functions in humans. In males, the primary sex organ is the testis, whereas in females, it includes the ovaries, corpus luteum, and placenta. The testes are responsible for producing sperm and androgens, like testosterone, vital for sexual maturation and reproductive functions. The ovaries in females secrete hormones such as estrogen and are involved in the production of gametes, specifically egg cells.