A type of detergent in which the active part of the molecule is a positive ion (cation) is known as cationic detergents are usually quaternary ammonium salts and often also have bactericidal properties. Cationic-detergents contains a long-chain cations that is responsible for their surface-active properties. Cationic detergents also possess excellent germicidal properties and are utilised in surgery in dilute form, it is not cheap and widely used. Hence, the correct option is (d).