Which is correct about
Assertion a. Knee joint is hinge joint. Reason r. Femur, patella and fibula are associated with knee joint.

Options

A. a is correct but r is wrong.
B. Both correct with r being explanation of a
C. a is wrong but r is correct
D. Both a and r are correct but r is not correct explanation of a.

Answer

To analyze the given assertion and reason regarding the knee joint, let's break it down step by step.

### Step-by-Step Solution:

1. **Understand the Assertion**: The assertion states that "the knee joint is a hinge joint."
- A hinge joint allows movement primarily in one direction, similar to the way a door opens and closes. In this case, the knee joint permits flexion (bending) and extension (straightening).

2. **Evaluate the Reason**: The reason provided is "femur, patella, and fibula are associated with the knee joint."
- The knee joint is indeed formed by the femur (thigh bone), patella (kneecap), and tibia (shin bone). The fibula is located next to the tibia but does not directly articulate with the knee joint.

3. **Check the Validity of Both Statements**:
- The assertion is **correct** because the knee joint is classified as a hinge joint.
- The reason is **partially correct** because while the femur and patella are associated with the knee joint, the fibula does not play a direct role in the knee joint's articulation.

4. **Determine the Relationship**:
- Both statements are correct, but the reason does not adequately explain the assertion. The reason should specifically mention the role of the femur and patella in the hinge movement of the knee joint.

5. **Conclusion**:
- The assertion is correct, and the reason is correct but does not explain the assertion. Therefore, we conclude that the assertion is true, but the reason is not a valid explanation for the assertion.

### Final Answer:
- Assertion is correct, Reason is correct but does not explain the assertion.