$CH_3Br\quad\underrightarrow{KCN}\quad A \quad\underrightarrow{+ 4H}\quad CH_3CH_2NH_2$ $ IUPAC$ name of $A$ is

Question

$\begin {array} {1 1} (A)\;\text{Methyl cynide} & \quad (B)\;\text{Methyl isonitrile} \\ (C)\;\text{Acetonitrile} & \quad (D)\;\text{Ethane nitrile} \end {array}$