Assertion : The energy `(E )` and momentum `(p)` of a photon are related by `p = E//c`.
Reason : The photon behaves like a particle.

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 the assertion and reason provided:

### Step 1: Understanding the Assertion
The assertion states that the energy \( E \) and momentum \( p \) of a photon are related by the equation:
\[ p = \frac{E}{c} \]
where \( c \) is the speed of light. This relationship is derived from the principles of quantum mechanics and special relativity.

### Step 2: Deriving the Relationship
1. **Energy of a Photon**: The energy of a photon can be expressed as:
\[ E = h \nu \]
where \( h \) is Planck's constant and \( \nu \) is the frequency of the photon.

2. **Momentum of a Photon**: The momentum \( p \) of a photon can also be expressed using its wavelength \( \lambda \):
\[ p = \frac{h}{\lambda} \]

3. **Relating Wavelength and Frequency**: The wavelength \( \lambda \) and frequency \( \nu \) are related by the equation:
\[ c = \lambda \nu \implies \lambda = \frac{c}{\nu} \]

4. **Substituting Wavelength into Momentum Equation**:
\[ p = \frac{h}{\lambda} = \frac{h \nu}{c} \]
Since \( E = h \nu \), we can substitute \( E \) into the momentum equation:
\[ p = \frac{E}{c} \]

### Step 3: Understanding the Reason
The reason states that "the photon behaves like a particle." This is consistent with the concept of wave-particle duality in quantum mechanics, where photons exhibit both wave-like and particle-like properties.

### Step 4: Conclusion
Both the assertion and the reason are correct:
- The assertion \( p = \frac{E}{c} \) is a valid relationship for photons.
- The reason correctly explains that photons behave like particles, which justifies the assertion.

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