Oral contraceptive pills used by females, function through:

The correct answer is Option (2) → Inhibiting ovulation and implantation

Option (1) Phagocytosis of sperms within uterus — Incorrect. This is how IUDs work. An IUD in the uterus increases the phagocytosis (engulfing) of sperms there.

Option (2) Inhibiting ovulation and implantation — Correct. The hormones of the pill stop the release of the ovum and prevent the embryo from implanting. They also change the cervical mucus so that sperms cannot enter easily.

Option (3) Suppressing sperm motility and fertilising capacity of sperm — Incorrect. This is the action of copper releasing IUDs. The Cu ions they release weaken the movement and the fertilising power of the sperms.

Option (4) Blocking gamete transport and thereby preventing conception — Incorrect. This is how sterilisation works. In vasectomy and tubectomy a small part of the vas deferens or the fallopian tube is removed or tied, so the gametes cannot pass.

NCERT Extract:
Population Stabilisation and Birth Control – “… Oral administration of small doses of either progestogens or progestogen–estrogen combinations is another contraceptive method used by the females. They are used in the form of tablets and hence are popularly called the pills. Pills have to be taken daily for a period of 21 days starting preferably within the first five days of menstrual cycle. After a gap of 7 days (during which menstruation occurs) it has to be repeated in the same pattern till the female desires to prevent conception. They inhibit ovulation and implantation as well as alter the quality of cervical mucus to prevent/retard entry of sperms.”