Answer:
A. by covering the cervix and blocking sperm from entering the uterus
Step-by-step explanation:
Contraception comes in many different ways. One popular method is by using "birth control pills." This pills are taken orally by women and once it works its way into the system, it thickens the woman's cervical mucus. Once this happens, the sperm cannot travel through; thus, the sperm will be blocked from passing through the cervix. This means "no fertilization" happens because the sperm cells cannot meet with the egg cells.
Fertilization is very important in order for a pregnancy to occur. So in this case, the birth control pills do prevent pregnancy.