Which of the following, when used within 72 hours of coitus, has been…

The correct answer is Option (1) → Intra-uterine devices (IUDs)

An emergency contraceptive is used after coitus has already taken place, to avoid a possible pregnancy after rape or casual unprotected intercourse. NCERT says progestogens, progestogen-estrogen combinations or IUDs used within 72 hours of coitus are very effective for this.

Option (1) Intra-uterine devices (IUDs) — Correct. IUDs inserted within 72 hours of coitus are named by NCERT as very effective emergency contraceptives.

Option (2) Condoms — Incorrect. A condom works only if it is used during coitus. Once semen has entered the female tract, a condom can do nothing.

Option (3) Lactational amenorrhea — Incorrect. Lactational amenorrhea depends on intense breast-feeding after childbirth. It is not something that can be started after one act of coitus.

Option (4) Vasectomy — Incorrect. Vasectomy is a terminal surgical method for the male. It cannot stop a pregnancy from coitus that has already taken place.

NCERT Extract:
Population Stabilisation and Birth Control – “… Their mode of action is similar to that of pills and their effective periods are much longer. Administration of progestogens or progestogen-estrogen combinations or IUDs within 72 hours of coitus have been found to be very effective as emergency contraceptives as they could be used to avoid possible pregnancy due to rape or casual unprotected intercourse.”