Identify the compound that will react with Hinsberg's reagent to give a solid which dissolves in alkali.

Hinsberg's reagent is Benzene sulfonyl chloride (${\text{C}}_6{\text{H}}_5{\text{SO}}_2\text{Cl}$).Primary Amines ($\text{R}-{\text{NH}}_2$) react to form sulfonamides that have an acidic Hydrogen on Nitrogen. This makes them soluble in alkali.Secondary Amines react but the product is insoluble in alkali (no acidic Hydrogen).Tertiary Amines do not react.Option A is Ethylamine (primary), so it dissolves in alkali after reaction.