Assertion: Phenol forms `2,4,6-`tribromophenol on treatement with `Br_(2)` water at `373K`.
Reason: Phenol is `o-p`-directing group.

Options

A. If both assertion and reason are correct and reason is correct explanation for assertion.
B. If both assertion and reason are correct but reason is not correct for assertion.
C. If assertion is correct but reason is incorrect.
D. If both assertion and reason are incorrect.

Explanation

To solve the question regarding the assertion and reason about phenol and its reaction with bromine water, we will break down the information step by step.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that phenol forms 2,4,6-tribromophenol when treated with bromine water at 373 K.
- This reaction involves the substitution of bromine atoms on the benzene ring of phenol.

2. **Reaction Mechanism**:
- When phenol (C6H5OH) is treated with bromine water (Br2 in water), the bromine reacts with the aromatic ring.
- The hydroxyl group (-OH) in phenol is an activating group that increases the electron density of the benzene ring.

3. **Formation of 2,4,6-Tribromophenol**:
- The bromination occurs primarily at the ortho (2 and 6 positions) and para (4 position) sites due to the electron-donating nature of the -OH group.
- As a result, three bromine atoms are substituted, leading to the formation of 2,4,6-tribromophenol.

4. **Understanding the Reason**:
- The reason states that phenol is an ortho-para directing group.
- This is true because the -OH group donates electron density to the benzene ring, making the ortho and para positions more reactive towards electrophilic substitution.

5. **Conclusion**:
- Both the assertion and the reason are correct.
- The reason provided is a correct explanation for the assertion since the ortho-para directing nature of phenol facilitates the formation of 2,4,6-tribromophenol.

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