Phenol is more reactive than benzene towards electrophilic substitution reaction.
In case of Phenol, the intermediate carbocation is more resonance stabilised.

Options

A. Statement `I` is true, Statement `II` is true , Statement `II` is the correct explanation of Statement `I`.
B. Statement `I` is true , Statement `II` is true , Statement `II` is not the correct explanation of Statement `I`
C. Statement `I` is true , Statement `II` is false.
D. Statement `I` is false , Statement `II` is true.

Explanation

### Step-by-Step Solution

1. **Understanding Electrophilic Substitution Reaction**:
- Electrophilic substitution reactions involve the substitution of a hydrogen atom in an aromatic compound by an electrophile. The reaction proceeds through the formation of a sigma complex (also known as an arenium ion), which is a carbocation intermediate.

2. **Comparing Benzene and Phenol**:
- Benzene is a stable aromatic compound with a delocalized π-electron system. When an electrophile attacks benzene, the π-electrons are used to form a bond with the electrophile, resulting in a sigma complex.
- In the case of phenol, the presence of the hydroxyl (-OH) group significantly affects the reactivity. The oxygen atom has lone pairs of electrons that can participate in resonance.

3. **Formation of Sigma Complex in Benzene**:
- When an electrophile attacks benzene, the π-electrons shift to form a bond with the electrophile, creating a positively charged sigma complex. This carbocation is less stable because it lacks additional stabilization mechanisms.

4. **Formation of Sigma Complex in Phenol**:
- In phenol, when an electrophile attacks, the lone pair of electrons on the oxygen can delocalize into the aromatic ring. This results in a sigma complex where the positive charge can be stabilized by resonance with the oxygen's lone pair. This additional stabilization makes the carbocation intermediate more stable than that of benzene.

5. **Resonance Stabilization**:
- The resonance structures of the sigma complex in phenol show that the positive charge can be distributed over multiple atoms, including the oxygen atom. This delocalization of charge through resonance (p-pi backbonding) enhances the stability of the carbocation.

6. **Conclusion**:
- Since the sigma complex formed from phenol is more resonance-stabilized than that formed from benzene, phenol is more reactive towards electrophilic substitution reactions compared to benzene. Therefore, both the assertion and the reason provided in the question are correct.

### Final Answer
- The assertion is true: "Phenol is more reactive than benzene towards electrophilic substitution reaction."
- The reason is also true: "In case of phenol, the intermediate carbocation is more resonance stabilized."
- Thus, the correct answer is (A) Both assertion and reason are correct, and the reason explains the assertion.