Which one of the following undergoes reaction with 50% sodium hydroxide solution to give the corresponding alcohol and acid?

Phenol Benzaldehyde  Butanal Benzoic acid

Benzaldehyde

Benzaldehyde undergoes reaction with 50% sodium hydroxide solution to give benzyl alcohol and benzoic acid. This is an example of Cannizzaro Reaction which is a redox disproportionation reaction.