Which one of the following is the most likely root cause why menstruation is not taking place in regularly cycling human female?

(A)Maintenance of the hypertrophical endometrial lining
(B)Maintenance of high concentration of sexhormones in the blood stream
(C)Retention of well-developed corpus luteum
(D)Fertilisation of the ovum

The NCERT line that answers it

Verbatim line

Menstruation only occurs if the released ovum is not fertilised.

Chapter: Human Reproduction
Section: 2.4 MENSTRUAL CYCLE

The answer appears as a continuous sentence in NCERT. This is that sentence.

How this line gives the answer

0, emb=1.0, combined=1.0). Verified: high — The span 'Menstruation only occurs if the released ovum is not fertilised' directly states that fertilization prevents menstruation, which is the specific biological fact that makes option D correct.

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Question text is reproduced from the published NEET 2009 paper for study and commentary. NCERT text is quoted, not redistributed; textbooks remain at ncert.nic.in. Our mapping method, including its measured error rates, is published at /methodology.