b
\(\underset{methyl\, iso-cynide}{\mathop{C{{H}_{3}}-\overset{+}{\mathop{N}}\,\,\,\equiv \,\,\overset{-}{\mathop{C}}\,\,}}\,\,\underset{\underset{reduction}{\mathop{LiAl{{H}_{4}}}}\,}{\mathop{\xrightarrow{4[H]}}}\,\,\underset{\begin{smallmatrix}dimethyl\, amine(2°amine)\end{smallmatrix}}{\mathop{C{{H}_{3}}NHC{{H}_{3}}}}\,\)