Vaults, cervical caps, diaphragms prevent conception by

The correct option is A blocking the entry of sperms
Vaults, cervical caps and diaphragms are the names of different types of barriers that are used as a method of contraception exclusively by females. These are dome-shaped made with rubber or plastic caps that are fitted in the vagina so as to cover the cervix of the female. The main principle of such contraceptives is to prevent conception by blocking the entry of sperms through the cervix.

Phagocytosis, suppressing the motility of the sperms and making the uterus unsuitable for implantation are the characteristics of intrauterine devices (IUDs) inserted inside the uterus through the vagina by medical professionals.