Which of the following reactions is characteristic of Phase II drug metabolism?

Phase II drug metabolism is characterized by conjugation reactions, where drug metabolites undergo further modification to increase their solubility and facilitate excretion from the body. Sulfation is a key phase II reaction involving the addition of a sulfate group to the drug or its metabolite, significantly enhancing its water solubility. This conjugation typically occurs in the liver and is catalyzed by sulfotransferase enzymes.

Amidation, while it may involve the formation of an amide bond, is not typically considered a primary phase II reaction. Hydrolysis primarily pertains to phase I metabolism reactions, where drugs are broken down into more polar metabolites without conjugation. Oxidation, also a hallmark of phase I metabolism, introduces or exposes functional groups but does not involve conjugation, which is the main feature of phase II reactions. Thus, sulfation is the most representative of phase II metabolic processes, making it the correct choice in this context.