In the calomel half cell,the reduction $rx_n$ is

Question

$\begin{array}{1 1}(A)\;Hg_2Cl_2(s)+2e^- \rightleftarrows 2Hg(l)+2Cl^-\\(B)\;Pb(s)+PbO_2+2H_2SO_4\rightarrow 2PbSO_4(s)+2H_2O(l)\\(C)\;2Hg+2Cl^-\rightarrow Hg_2Cl_2+2e^-\\(D)\;Cr_2O_7^{2-}(aq)+14H^+(aq)+6e^-\rightarrow 2Cr^{+3}(aq)+7H_2O\end{array}$