Assertion: The estrogen level falls after menopause.
Reason: The estrogen is synthesised and secreted mainly by uterine lining.

Options

A. (a) Both, Assertion and Reason, are true and Reason is the correct explanation of Assertion
B. (b) Both, Assertion and Reason, are true but Reason is not the correct explanation of Assertion
C. (c) If Assertion is true but Reason is false
D. (d) If Assertion is false but Reason is true

Explanation

**Step-by-Step Solution:**

1. **Understanding the Assertion**: The assertion states that "The estrogen level falls after menopause." This is a true statement. As women reach menopause, the ovaries gradually produce less estrogen, leading to a decrease in estrogen levels.

2. **Understanding the Reason**: The reason provided is "The estrogen is synthesized and secreted mainly by uterine lining." This statement is incorrect. Estrogen is primarily synthesized and secreted by the ovaries, not the uterine lining. While the uterine lining does respond to estrogen, it does not produce it.

3. **Evaluating the Relationship**: The assertion is true, but the reason is false. The reason does not correctly explain the assertion because it incorrectly identifies the source of estrogen production.

4. **Conclusion**: Based on the evaluation, the correct answer is that the assertion is true, but the reason is false. Therefore, the answer is option C: "Assertion is true but reason is false."