Question

question 17
how do hormonal contraceptives prevent pregnancy?
by maintaining consistent cervical mucus levels
by forming a physical barrier to female reproductive tract
by altering uterine fluids
by preventing ovulation

Explanation:

Hormonal contraceptives, such as birth - control pills, work mainly by preventing ovulation. They contain hormones (estrogen and progestin or progestin - only) that suppress the release of luteinizing hormone (LH) and follicle - stimulating hormone (FSH). Without a proper surge of LH, ovulation (the release of an egg from the ovary) does not occur.

Maintaining consistent cervical mucus levels is not the primary mechanism (though some hormonal contraceptives can thicken cervical mucus as a secondary effect). Forming a physical barrier is the mechanism of barrier methods like condoms or diaphragms, not hormonal contraceptives. Altering uterine fluids is not the main way hormonal contraceptives prevent pregnancy.

Answer:

by preventing ovulation