Assertion :- Maximum thickness of endometrium is present on `23^(rd)` day of m.c.
Reason :- Maximum level of progesterone is found on `22^(nd)` day of m.c.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are False.

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that the maximum thickness of the endometrium is present on the 23rd day of the menstrual cycle (MC).
- The endometrium is the inner lining of the uterus, which thickens in preparation for a potential pregnancy.

2. **Understanding the Reason**:
- The reason states that the maximum level of progesterone is found on the 22nd day of the menstrual cycle.
- Progesterone is a hormone produced by the corpus luteum after ovulation, which plays a crucial role in preparing the endometrium for implantation.

3. **Analyzing the Menstrual Cycle**:
- The menstrual cycle can be divided into four phases:
- **Menstruation Phase**: Days 1-5, where the endometrium sheds.
- **Follicular Phase**: Days 6-14, where follicles mature and estrogen levels rise.
- **Ovulation**: Occurs around day 14, when an egg is released.
- **Luteal Phase**: Days 15-28, where the corpus luteum forms and secretes progesterone.

4. **Linking the Assertion and Reason**:
- During the luteal phase, progesterone levels peak around the 22nd day, which is crucial for the thickening of the endometrium.
- The thickening of the endometrium reaches its maximum around the 23rd day due to the effects of progesterone.

5. **Conclusion**:
- Both the assertion and the reason are true.
- The reason correctly explains why the assertion is true, as the rise in progesterone leads to the maximum thickness of the endometrium.

### Final Answer:
- Both the assertion and the reason are true, and the reason correctly explains the assertion.