[A] : Cartilage (Protein matrix) and Bone (Cal- cium matrix) are rigid connective tissue.
[R]: Blood is a connective tissue in which plasma is the matrix.

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

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

### Step-by-Step Solution:

1. **Identify the Assertion (A)**:
- The assertion states that "Cartilage (Protein matrix) and Bone (Calcium matrix) are rigid connective tissue."
- **Analysis**: This statement is true. Cartilage is made up of a protein matrix, which gives it flexibility, while bone is composed of a calcium matrix, making it rigid. Both are classified as connective tissues.

2. **Identify the Reason (R)**:
- The reason states that "Blood is a connective tissue in which plasma is the matrix."
- **Analysis**: This statement is also true. Blood is indeed classified as a connective tissue, and its matrix is plasma, which is a fluid.

3. **Determine the Relationship**:
- We need to assess whether the reason provided correctly explains the assertion.
- While both statements are true, the reason does not explain why cartilage and bone are considered rigid connective tissues. Instead, it discusses blood, which is a different type of connective tissue.

4. **Conclusion**:
- Since both the assertion and reason are true, but the reason does not explain the assertion, the correct answer is that both are true, but the reason is not the correct explanation of the assertion.

### Final Answer:
The correct option is: **Both assertion and reason are true, but reason is not the correct explanation of assertion.**

---