Identify $A, B$ and $C$ in the following reactions:
$CH_3 Cl$ $\xrightarrow{KCN} A$ $\xrightarrow{H_3 O^{\oplus}} B$ $\xrightarrow{C_2 H_5 OH / H^{+}, \Delta} C$

• A
  $A = CH_3 NC, B = CH_3 NHCH_3, C = CH_3 N(CH_3)C_2 H_5$
• B
  $A = CH_3 CN, B = CH_3 CONH_2, C = CH_3 CO_2 H$
• C
  $A = CH_3 CN, B = CH_3 CO_2 H, C = CH_3 CO_2 C_2 H_5$
• D
  $A = CH_3 CN, B = CH_3 CO_2 H, C = (CH_3 CO)_2 O$