Diaphragms are barrier methods of contraception that cover the cervix and block the entry of sperms (a-iv). Contraceptive pills contain progestogens or a combination of progestogen and oestrogen, which inhibit ovulation and implantation (b-i). Intra uterine devices increase the phagocytosis of sperms within the uterus (c-ii). Lactational amenorrhea is a natural method of contraception based on the absence of the menstrual cycle and ovulation following parturition (d-iii). Therefore, the correct match is a-(iv), b-(i), c-(ii), d-(iii).