The action of which of the following hormone is blocked during the use of RU 486 (mifepristone) ?

Options

A. FSH
B. LH
C. Progesterone
D. hCG

Answer

To answer the question regarding which hormone's action is blocked during the use of RU 486 (mifepristone), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding RU 486 (Mifepristone)**:
- RU 486, also known as mifepristone, is a medication used primarily for medical abortion. It is effective when taken within the first trimester of pregnancy (up to 63 days).

2. **Mechanism of Action**:
- Mifepristone works by blocking the action of certain hormones that are crucial for maintaining pregnancy.

3. **Identifying the Key Hormone**:
- The primary hormone that is inhibited by mifepristone is **progesterone**. Progesterone is essential for the growth and maintenance of the uterine lining during pregnancy.

4. **Effect of Blocking Progesterone**:
- By blocking progesterone, mifepristone leads to the breakdown of the uterine lining, which ultimately results in the termination of the pregnancy.

5. **Conclusion**:
- Therefore, the hormone whose action is blocked during the use of RU 486 (mifepristone) is **progesterone**.

### Final Answer:
The action of **progesterone** is blocked during the use of RU 486 (mifepristone).

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