A : Lenses of large aperture suffer from spherical aberration.
R : The curvature of the lens at central and peripheral regions is different.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statements, then mark (4).

Answer

To analyze the statements A and R, we need to break them down and evaluate their validity in the context of optics, particularly regarding spherical aberration in lenses.

### Step-by-Step Solution:

1. **Understanding Statement A**:
- Statement A claims that "Lenses of large aperture suffer from spherical aberration."
- This statement is **true**. Lenses with large apertures can indeed suffer from spherical aberration because light rays that strike the lens near the edge (peripheral rays) do not converge at the same point as those that strike near the center (central rays). This results in a blurred image.

2. **Understanding Statement R**:
- Statement R states that "The curvature of the lens at central and peripheral regions is different."
- This statement is also **true**. In a spherical lens, the curvature is generally greater at the edges compared to the center. This difference in curvature leads to varying focal points for rays entering the lens at different angles, contributing to spherical aberration.

3. **Relationship Between A and R**:
- Now we need to determine if R correctly explains A. While both statements are true, R does not provide a complete explanation for A. Spherical aberration arises not just from the difference in curvature but also from the thickness of the lens and the angle at which light rays enter the lens.
- Therefore, while R is true, it does not fully justify A.

4. **Conclusion**:
- Since A is true and R is true but does not explain A, we conclude that the relationship between the two statements is not valid in the context of a cause-and-effect explanation.

### Final Answer:
- A is true; R is true; R is not the correct explanation for A.