The correct option is B a - i, b - iii, c -ii, d -iv
Deliberate prevention of conception is called contraception.
Barrier method is one of the contraceptive methods in which the physical meeting of ovum and sperm is prevented. Vaults are barriers made of rubber inserted into the female reproductive tract to cover the cervix during coitus. Thus the entry of sperm is blocked.
IUDs are intrauterine devices inserted into the uterus by doctors or expert nurses. It's one of the most popular birth control methods. IUDs cause phagocytosis of sperms within the uterus.
Vasectomy is a surgical method of contraception and involves tying and cutting of vas deferens in males. Thus, vasectomy blocks the transport of sperms but does not stop the production of sperms.
Tubectomy is a surgical method of contraception performed in females in which the fallopian tubes are tied and cut. As the fallopian tubes are blocked, the egg released from the ovary is prevented from meeting the sperm. Thus, tubectomy prevents conception.