Hinsberg reagent is benzenesulfonyl chloride, whose formula is:
${\mathit{C}}_6{\mathit{H}}_5\mathit{S}{\mathit{O}}_2\mathit{C}\mathit{l}$
It is used in the Hinsberg test to distinguish between:
Primary amines
Secondary amines
Tertiary amines
The other options represent different compounds:
(A) ${\mathit{C}}_6{\mathit{H}}_5\mathit{C}\mathit{O}\mathit{C}\mathit{l}$ $\to$ Benzoyl chloride
(C) ${\mathit{C}}_6{\mathit{H}}_5\mathit{C}\mathit{O}\mathit{N}\mathit{H}\mathit{C}{\mathit{H}}_3$$\to$ An amide
(D) ${\mathit{C}}_6{\mathit{H}}_6\mathit{C}{\mathit{H}}_2\mathit{N}{\mathit{H}}_2$ $\to$ Benzylamine
Therefore, the correct formula of Hinsberg’s reagent is ${\mathit{C}}_6{\mathit{H}}_5\mathit{S}{\mathit{O}}_2\mathit{C}\mathit{l}$ .