Identify the hormone responsible for ovulation during menstrual cycle.

The correct answer is Option (4) → LH

During the follicular phase, the levels of LH and FSH rise slowly. Both reach a peak in the middle of the cycle, about the 14th day. The quick rise of LH to its highest level is called the LH surge. It makes the Graafian follicle burst and release the ovum. This is ovulation.

(1) Relaxin — Incorrect. Relaxin is a hormone secreted by the ovary in the later phase of pregnancy. It has no role in ovulation.

(2) Progesterone — Incorrect. Progesterone is made by the corpus luteum after ovulation. It keeps the lining of the uterus ready for implantation.

(3) FSH — Incorrect. FSH (follicle stimulating hormone) is a gonadotropin from the anterior pituitary. It makes the follicles grow during the follicular phase. It is the LH surge that makes the follicle rupture.

(4) LH — Correct. LH (luteinising hormone) is the other gonadotropin of the anterior pituitary. Its rapid rise in the middle of the cycle, the LH surge, makes the Graafian follicle rupture and release the ovum, so LH is the hormone responsible for ovulation.

NCERT Extract:
Menstrual Cycle – “… The secretion of gonadotropins (LH and FSH) increases gradually during the follicular phase, and stimulates follicular development as well as secretion of estrogens by the growing follicles. Both LH and FSH attain a peak level in the middle of cycle (about 14th day). Rapid secretion of LH leading to its maximum level during the mid-cycle called LH surge induces rupture of Graafian follicle and thereby the release of ovum (ovulation).”