The compound that will react with HBr most readily is:

Options

A. `(CH_(3))_(3)COH`
B. `(CH_(3))_(2)CHOH`
C. `CH_(3)CH_(2)OH`
D. `C_(6)H_(5)OH`

Explanation

To determine which compound reacts most readily with HBr, we need to analyze the reactivity of alcohols and phenols.

### Step-by-Step Solution:

1. **Identify the Compounds**: The compounds in question are alcohols and phenols. We need to understand their structures and how they react with HBr.

2. **Analyze Phenol**:
- Phenol has an -OH (hydroxyl) group attached to a benzene ring.
- The oxygen in the hydroxyl group has lone pairs of electrons, which can participate in resonance with the benzene ring.
- This resonance gives the -OH group partial double bond character, making it less reactive towards nucleophiles like HBr.
- Phenols do not readily react with halogens unless there are electron-withdrawing groups present to facilitate the reaction.

3. **Analyze Alcohols**:
- Alcohols can be classified into three types: primary, secondary, and tertiary.
- Tertiary alcohols are the most reactive towards hydrogen halides (like HBr) due to the formation of stable tertiary carbocations upon ionization.
- Secondary alcohols are less reactive than tertiary, and primary alcohols are the least reactive.

4. **Reactivity Order**:
- The order of reactivity of alcohols with HBr is: Tertiary > Secondary > Primary.
- Tertiary alcohols can react immediately with HBr, leading to the formation of a stable carbocation, which facilitates the substitution reaction.

5. **Conclusion**:
- Given that phenols are less reactive due to resonance stabilization and the presence of electron-withdrawing groups, and that tertiary alcohols react most readily with HBr, the compound that will react with HBr most readily is a tertiary alcohol.

### Final Answer:
The compound that will react with HBr most readily is a tertiary alcohol.