The correct option is B prevent conception by blocking the entry of sperm through the cervix
Barrier methods are the physical way of birth control wherein barriers are designed to restrict the movement of sperms within the female reproductive tract. Some of these barrier methods may also protect the individual from sexually transmitted disease (STDs). Diaphragms, cervical caps and vaults are a some of the barrier contraceptives used by women. They block the passage of sperms through the cervix of the female.
Copper releasing IUDs are the ones which have spermicidal properties as they increase the levels of prostaglandins and white blood cells within the uterus, thus causing phagocytosis of sperms. A high concentration of copper in semen can cause lower sperm motility and reduced fertilising capacity of sperms.