Ovulation is induced by -

The correct answer is Option (2) → Luteinizing hormone

In the follicular phase the levels of LH and FSH rise slowly. Both reach a peak in the middle of the cycle, around the 14th day. The sharp rise of LH at this time is called the LH surge. It makes the mature Graafian follicle burst and release the ovum. This release is ovulation.

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

(2) Luteinizing hormone — Correct. Luteinizing hormone is LH. The mid-cycle LH surge causes the Graafian follicle to rupture and release the ovum.

(3) Follicle stimulating hormone — Incorrect. FSH makes the follicles grow during the follicular phase. It is the LH surge, not FSH, that causes the follicle to rupture.

(4) Estrogen hormone — Incorrect. Estrogens are secreted by the growing follicles. They build up the uterine lining, but they do not cause the follicle to rupture.

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).”