The onset of the menstrual flow causes a drop in female hormone levels. The correct option is D.
<h3>What is the female hormone?</h3>
Estrogen is the female hormone that plays an important role in the reproductive development of women.
When the egg does not fertilize, the menstrual cycle begins, and this stops the production of female hormones.
Low estrogen levels cause irregular periods, and difficulty in getting pregnant.
Thus, the correct option is D.
Learn more about the female hormone
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