${\mathrm{CH}}_3\mathrm{Br}\underset{\mathrm{ether}}{\overset{\mathrm{Mg}}{\to }}\mathrm{A}\underset{ }{\overset{{\mathrm{CdCl}}_2}{\to }}\mathrm{B}\underset{ }{\overset{{\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2\mathrm{COCl}}{\to }};$ the compound ‘C’ in the reaction is

$$\begin{gathered} \mathrm{A} \mathrm{is} {\mathrm{CH}}_3\mathrm{MgBr}; \\ 2{\mathrm{CH}}_3\mathrm{MgBr}+{\mathrm{CdCl}}_2\stackrel{ }{\to }\underset{\left(\mathrm{B}\right)}{{\left({\mathrm{CH}}_3\right)}_2\mathrm{Cd}}+2\mathrm{Mg}\left(\mathrm{Br}\right)\mathrm{Cl} \\ 2{\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2\mathrm{COCl}+{\left({\mathrm{CH}}_3\right)}_2\mathrm{Cd}\underset{\left(\mathrm{C}\right)}{\stackrel{ }{\to }{\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{CH}}_2{\mathrm{COCH}}_3}+{\mathrm{CdCl}}_2 \end{gathered}$$