$\mathop {(A)}\limits_{ gives\,\,positive ~\\ iodoform\,Test } \xrightarrow[\begin{subarray}{l} (ii)\,{H^ + },{H_2}O + ~\\ (iii)\,conc.\,{H_2}S{O_4}/\Delta \end{subarray} ]{{{\text{(i) C}}{{\text{H}}_{\text{3}}}{\text{MgBr}}}}(B)\xrightarrow{{{O_3}/Zn,{H_2}O}}$
$[A]\,\,\begin{array}{*{20}{c}} {C{H_3} - C - {O^ - }} \\ {\,\,||} \\ {\,\,O} \end{array}$
$[B]\,\,CH_3O^-$
$[C]\,\,CN^-$
$[D]\,\,$