\(HCHO\xrightarrow{[Ag\left( N{{H}_{3}} \right)_{2}^{+}]}\underset{\text{ Silver mirror }}{\mathop{Ag\downarrow }}\,+\) Organic compound
\(C{{H}_{3}}-CHO\xrightarrow[S]{{{[Ag{{\left( N{{H}_{3}} \right)}_{2}}]}^{+}}}\underset{\text{ Silver mirror }}{\mathop{Ag\downarrow }}\,+\) Organic Compound
$[A]\,\,\begin{array}{*{20}{c}} {C{H_3} - C - {O^ - }} \\ {\,\,||} \\ {\,\,O} \end{array}$
$[B]\,\,CH_3O^-$
$[C]\,\,CN^-$
$[D]\,\,$