Read the given passage and answer the following questions:

The menstrual cycle starts with the menstrual phase, when menstrual flow occurs and it lasts for 3-5 days. The menstrual flow results due to breakdown of endometrial lining of the uterus and its blood vessels which forms liquid that comes out through vagina. Menstruation only occurs if the released ovum is not fertilised. Lack of menstruation may be indicative of pregnancy. However, it may also be caused due to some other underlying causes like stress, poor health etc. The menstrual phase is followed by the follicular phase. During this phase, the primary follicles in the ovary grow to become a fully mature Graafian follicle and simultaneously the endometrium of uterus regenerates through proliferation. These changes in the ovary and the uterus are induced by changes in the levels of pituitary and ovarian hormones. 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). The ovulation (ovulatory phase) is followed by the luteal phase during which the remaining parts of the Graafian follicle transform as the corpus luteum . The corpus luteum secretes large amounts of progesterone which is essential for maintenance of the endometrium.

Menstruation occurs only if the:

Ovum is not fertilized

The correct answer is Option (1) –Ovum is not fertilized

Menstruation occurs when the ovum (egg) released during ovulation is not fertilized by a sperm. In this case, the corpus luteum degenerates, and the levels of hormones like progesterone and estrogen drop. This hormonal drop leads to the breakdown of the endometrial lining (which had thickened in preparation for a potential pregnancy) and its shedding, resulting in menstrual flow.

If fertilization occurs, the corpus luteum continues to produce hormones, maintaining the endometrial lining to support a pregnancy, and menstruation does not take place.