Lactational amenorrhea refers to:

The correct answer is Option (2) → Absence of menstruation during intense lactation

Lactational amenorrhea is a natural method of contraception. While the mother breast-feeds the baby fully, ovulation and the menstrual cycle do not occur, so the chance of conception is nearly nil.

Option (1) Absence of menstruation — Incorrect. This is only amenorrhea, which can have many causes. It leaves out the link with lactation.

Option (2) Absence of menstruation during intense lactation — Correct. It names both parts of the term: no menstruation, because of intense breast-feeding after parturition.

Option (3) No breast feeding — Incorrect. It is the opposite. Without breast-feeding the cycle soon returns and the method fails.

Option (4) Intense breast feeding — Incorrect. Intense breast-feeding is the condition that causes lactational amenorrhea, not the amenorrhea itself.

NCERT Extract:
Population Stabilisation and Birth Control – “… Withdrawal or coitus interruptus is another method in which the male partner withdraws his penis from the vagina just before ejaculation so as to avoid insemination. Lactational amenorrhea (absence of menstruation) method is based on the fact that ovulation and therefore the cycle do not occur during the period of intense lactation following parturition.”