An aqueous solution of salt is alkaline. It shows that the salt is made from:

Strong acid and strong base create a neutral or normal salt because the salt's cation and anion are both weak and do not fully hydrolyze. These salts, which lack replacement hydrogen or hydroxyl, are created when acids and bases neutralize. Strong acid and a weak base combine to generate an acidic salt. Caionic hydrolysis is the cause of its acidity. A strong base has a weak conjugate acid. As a result, it experiences cationic hydrolysis and transforms into an acidic salt. Both the cation and anion undergo hydrolysis, making the salt of a weak acid and weak base neutral. When dissolved in water, a salt created by the interaction of a strong base and weak acid has an alkaline character.

A salt of strong acid and strong base is neutral.

A salt of strong acid and a weak base is acidic in nature.

A salt of a strong base and weak acid is basic in nature. If the aqueous solution of salt is alkaline it is made from strong alkali and weak acid.

Hence, option D is correct.