Which functional groups have the highest priority in nomenclature?

In organic chemistry, the priority of functional groups in nomenclature is based on the hierarchy established by the International Union of Pure and Applied Chemistry (IUPAC). Carboxylic acids and anhydrides have the highest priority among the functional groups, which is why the correct answer is the option that includes them.

Carboxylic acids, identified by the -COOH group, are ranked very high due to the presence of the carbonyl (C=O) and hydroxyl (OH) groups together, making them strongly acidic and influencing the structure's reactivity. Anhydrides, which are formed from carboxylic acids by the removal of water, also hold a high position in the priority order because they retain the functional character of the carboxylic acid group.

Ketones and aldehydes are less prioritized than carboxylic acids and anhydrides, even though they significantly influence reactivity and properties in organic compounds. Aldehydes feature a carbonyl group bonded to at least one hydrogen atom, while ketones are bonded to two carbon atoms—it places them below the carboxylic acid functional group.

Alcohols and ethers, which consist of hydroxyl groups or ether linkages (-R-O-R'),