The amine that reacts will Hinsberg's reagent to give an alkali...

Secondary amines on reaction with Hinsberg's reagent (benzene sulphonyl chloride) forms $\mathrm{N}, \mathrm{N}$-dialkyl benzene sulphonamide. The product formed is not acidic as no $\mathrm{H}$-atom is attached to $\mathrm{N}$ thus it is insoluble in alkali. The reaction of $2^{\circ}$ amine given in option (1) takes place as follows:

On the other hand, $1^{\circ}$ amines react with Hinsberg's reagent to yield $\mathrm{N}$-alkyl benzene sulphonamide which is soluble in alkali and $3^{\circ}$ amines do not react with $\mathrm{C}_6 \mathrm{H}_5 \mathrm{SO}_2 \mathrm{Cl}$. The remaining options contain $1^{\circ}$ and $3^{\circ}$ amines.
Thus, option (1) is correct.