Inhibition of uterine contraction casses and the bleeding and cramps of menstruation begin due to

Options

A. Increase in level of progesterone
B. Decrease in level of progesterone
C. Increase in level of LH
D. Decrease in level of FSH

Answer

To solve the question regarding the inhibition of uterine contractions and the onset of menstruation, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Menstrual Cycle**: The menstrual cycle involves various hormonal changes that regulate the preparation and shedding of the uterine lining (endometrium).

2. **Role of Progesterone**: Progesterone is a hormone produced by the corpus luteum (the remnant of the follicle after ovulation). It plays a crucial role in maintaining the endometrium and preventing contractions of the uterus.

3. **Decrease in Progesterone**: At the end of the menstrual cycle, if fertilization does not occur, the corpus luteum degrades. This leads to a decrease in progesterone levels.

4. **Effects of Decreased Progesterone**: The decrease in progesterone causes the endometrium to lose its support and begin to break down. This breakdown leads to the shedding of the uterine lining, resulting in menstrual bleeding.

5. **Cramps and Bleeding**: As the endometrium sheds, it can cause cramps due to uterine contractions. Therefore, the cessation of uterine contraction is linked to the decrease in progesterone levels.

6. **Conclusion**: Based on the above understanding, the correct answer to the question is that the inhibition of uterine contractions and the onset of bleeding and cramps during menstruation is due to a decrease in the level of progesterone.

### Final Answer:
The correct option is **B) decrease in the level of progesterone**.

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