$ Rhodopsin of rod cells and iodospin of cone cells of retina are proteins
! Myosine and Actin are contractile proteins

Options

A. If both As and R are correct and R is correct explanation of As
B. If both As and R are correct but R is not correct explanation of As
C. If As is correct, R is wrong
D. If both As and R are wrong.

Answer

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "Rhodopsin of rod cells and iodopsin of cone cells of retina are proteins."
- **Explanation**: Rhodopsin is a light-sensitive pigment found in rod cells, which are responsible for vision in low light conditions. Iodopsin is found in cone cells, which are responsible for color vision and function best in bright light. Both of these pigments are indeed proteins.

2. **Understanding the Reason**: The reason states that "Myosin and Actin are contractile proteins."
- **Explanation**: Myosin and actin are proteins that play crucial roles in muscle contraction. Myosin is a thick filament, while actin is a thin filament. Together, they facilitate the sliding mechanism that allows muscles to contract.

3. **Evaluating the Assertion and Reason**:
- Both the assertion and the reason are correct statements.
- However, the reason provided (about myosin and actin being contractile proteins) does not explain why rhodopsin and iodopsin are proteins. The two statements are related to different functions and types of proteins.

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

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

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