Final answer:
Hormonal contraceptives suppress ovulation by inhibiting FSH and LH secretion, preventing the release of an egg and thus fertilization. So the correct option is a.
Step-by-step explanation:
The BEST explanation of how hormonal contraceptives work is they suppress ovulation. Hormonal contraceptives contain synthetic forms of hormones like estrogen and progestin that work by inhibiting the secretion of Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH). This suppression prevents the release of an egg from the ovaries (ovulation), which means there's no egg available for sperm to fertilize. Moreover, they make changes to the uterine lining and cervical mucus, impairing sperm mobility and contributing to the prevention of fertilization.