Final answer:
Selenium is essential for the conversion of hormones in the reproductive system, such as LH to testosterone in men and FSH to estrogens and progesterone in women.
Step-by-step explanation:
Selenium is involved in the conversion of hormones in the reproductive system. In men, it plays a role in the conversion of luteinizing hormone (LH) to testosterone in the Leydig cells of the testes. In women, it is involved in the conversion of follicle-stimulating hormone (FSH) to estrogens and progesterone in the ovary. Selenium is essential for the proper functioning of these hormones and the reproductive system as a whole.