The major product of the reaction between $\mathrm{m}$-dinitrobenzene with ${\mathrm{NH}}_4\mathrm{HS}$ is :

${\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{Cl}\stackrel{\mathrm{NaCN}}{\to } \mathrm{x} \stackrel{\mathrm{Ni}/{\mathrm{H}}_2}{\to }\mathrm{y} \underset{\mathrm{anhydride}}{\overset{\mathrm{Acetic}}{\to }}\mathrm{z}$ 

Identify $\mathrm{z}$ in the above reaction, from the following.