Identify $A$ and $B$ in the following reaction.

(A) The reaction proceeds in two steps:
$1$. The starting material is $2-(2-chloroethyl)cyclohexanone$. Treatment with $KCN$ leads to a nucleophilic substitution reaction where the $Cl^-$ ion is replaced by the $CN^-$ group,forming $A$,which is $3-(2-oxocyclohexyl)propanenitrile$.
$2$. The subsequent reduction of the nitrile group $(-CN)$ using $H_2/Pd$ (catalytic hydrogenation) reduces the nitrile to a primary amine $(-CH_2NH_2)$,forming $B$,which is $2-(3-aminopropyl)cyclohexanone$.