Assertion : In interference and diffraction, light energy is redistributed.
Reason : There is no gain or loss of energy, which is consistent with the principle of conservation of energy.

Options

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

Explanation

To solve the question regarding the assertion and reason related to interference and diffraction, we can break it down into clear steps:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that in interference and diffraction, light energy is redistributed. This means that when two or more light waves overlap, they combine in such a way that their energy is not lost but rather rearranged.

2. **Understanding the Reason**:
- The reason provided states that there is no gain or loss of energy, which aligns with the principle of conservation of energy. This principle asserts that energy cannot be created or destroyed, only transformed from one form to another.

3. **Analyzing Interference**:
- In interference, when two coherent light waves meet, they superpose. This leads to the formation of bright and dark fringes. Bright fringes occur where the waves constructively interfere (energy is combined), while dark fringes occur where they destructively interfere (energy is canceled out).
- The energy that is "lost" in the dark fringes is exactly equal to the energy that is "gained" in the bright fringes. Thus, the total energy remains constant.

4. **Analyzing Diffraction**:
- In diffraction, light waves bend around obstacles and spread out after passing through narrow openings. This also leads to a redistribution of light energy across different regions.
- Similar to interference, diffraction patterns exhibit areas of high intensity (bright regions) and low intensity (dark regions), maintaining the conservation of energy.

5. **Conclusion**:
- Both the assertion and the reason are true. The assertion correctly describes the redistribution of light energy in interference and diffraction, and the reason accurately explains that this redistribution does not violate the conservation of energy principle.

### Final Answer:
Both the assertion and the reason are true, and the reason is the correct explanation of the assertion.