Question

which causes a drop in female hormone levels?
the onset of the menstrual flow
the release of an egg from the ovary
the thickening of the uterine wall
the failure of an egg to be fertilized

Explanation:

To determine what causes a drop in female hormone levels, we analyze each option:

• "The onset of the menstrual flow" is a result of hormone changes, not the cause of the drop.
• "The release of an egg from the ovary" (ovulation) is associated with a surge in hormones, not a drop.
• "The thickening of the uterine wall" is due to hormone stimulation, not a cause of hormone drop.
• "The failure of an egg to be fertilized" leads to the breakdown of the corpus luteum, which causes a drop in progesterone and estrogen (female hormones) as the body prepares for menstruation.

Answer:

the failure of an egg to be fertilized