Assertion : Ball and socket joints are the most mobile joints.
Reason: Synovial fluid is present here.

Options

A. If both Assertion and Reason are ture and the Reason is the correct explanation of the Assertion.
B. If both Assertion and Reason are ture, but the Reason is not the correct explanation of the Assertion.
C. If Asserion is ture, but Reason is false .
D. If both Assertion and Reason are false.

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Ball and socket joints are the most mobile joints."
- This is true because ball and socket joints, such as the shoulder and hip joints, allow for a wide range of motion in multiple directions.

2. **Understanding the Reason**:
- The reason given is "Synovial fluid is present here."
- This statement is also true. Synovial fluid is a thick, sticky fluid found in the synovial cavity of joints, which helps lubricate the joints and reduce friction during movement.

3. **Analyzing the Relationship**:
- We need to determine if the reason provided is the correct explanation for the assertion.
- While synovial fluid contributes to the mobility of joints by providing lubrication, the primary reason that ball and socket joints are the most mobile is their structural arrangement. The spherical head of one bone fits into the cup-shaped socket of another bone, allowing for movement in various planes.

4. **Conclusion**:
- Both the assertion and reason are true, but the reason is not the correct explanation for the assertion.
- Therefore, the answer is that the assertion is true, the reason is true, but the reason does not correctly explain the assertion.

### Final Answer:
- Assertion: True
- Reason: True
- Explanation: The reason is not the correct explanation of the assertion.