The correct option is A CH3CH2CHO
Cannizzaro reaction is a chemical reaction named after Stanislao Cannizzaro that involves the base-induced disproportionation of two molecules of a non-enolizable aldehyde to yield a carboxylic acid and a primary alcohol.
Aldehydes which contain α− hydrogens in them do not give cannizzaro's reaction.
As propanaldehyde is the only compound with α hydrogens, So, it will not undergo cannizzaro reaction.
Hence, Option "a" is the correct answer.