Which one of the following compounds will readily react with dilute NaOH?

Since NaOH is a base, we need to find which compound is sufficiently acidic to react with dilute NaOH.

Ethanol ($$C_2H_5OH$$) is an aliphatic alcohol with very weak acidity (pKa ~ 16), so it does not react with dilute NaOH.

Phenol ($$C_6H_5OH$$) is a weak acid (pKa ~ 10) due to resonance stabilization of the phenoxide ion; it readily reacts with NaOH:

$$C_6H_5OH + NaOH \rightarrow C_6H_5ONa + H_2O$$

Benzyl alcohol ($$C_6H_5CH_2OH$$) is a primary alcohol and not acidic enough to react with dilute NaOH, and tert-butanol ($$(CH_3)_3COH$$) is a tertiary alcohol that likewise does not react with dilute NaOH.

Therefore, among the given compounds only phenol ($$C_6H_5OH$$) is acidic enough to react with dilute NaOH. The correct answer is Option 2: $$C_6H_5OH$$.