Assertion : The threshold frequency of photoelectric effect supports the particle nature of light.
Reason : If frequency of incident light is less than the threshold frequency, electrons are not emitted from metal surface.

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, we need to analyze both the assertion and the reason provided in the context of the photoelectric effect.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "The threshold frequency of photoelectric effect supports the particle nature of light."
- In the photoelectric effect, light is considered to consist of particles called photons. Each photon has energy proportional to its frequency (E = hf, where h is Planck's constant and f is the frequency).
- The threshold frequency (f₀) is the minimum frequency of light required to eject electrons from a metal surface. If the frequency of the incident light is equal to or greater than this threshold frequency, electrons are emitted.

2. **Understanding the Reason**:
- The reason states that "If the frequency of incident light is less than the threshold frequency, electrons are not emitted from the metal surface."
- This is a direct consequence of the photoelectric effect. If the energy of the incoming photons (which depends on their frequency) is less than the work function of the metal (the minimum energy needed to eject an electron), then no electrons will be emitted.

3. **Evaluating the Truth of Assertion and Reason**:
- Both the assertion and the reason are true statements based on the principles of the photoelectric effect.
- The assertion correctly identifies that the threshold frequency is indicative of the particle nature of light because it involves photons.
- The reason correctly explains a condition of the photoelectric effect.

4. **Determining the Relationship Between Assertion and Reason**:
- While both statements are true, the reason does not provide a direct explanation for the assertion. The assertion discusses the particle nature of light, while the reason focuses on the condition for electron emission.
- Therefore, the reason is true, but it does not explain why the threshold frequency supports the particle nature of light.

### Conclusion:
- Both the assertion and the reason are true, but the reason is not the correct explanation for the assertion.