$A$ solution containing $1 \ mol \ L^{-1}$ of each $Cu(NO_3)_2, AgNO_3, Hg_2(NO_3)_2$ and $Mg(NO_3)_2$ is being electrolysed using inert electrodes. The standard reduction potentials are $E^0_{Ag^{+}/Ag} = +0.80 \ V, E^0_{Hg_2^{2+}/Hg} = +0.79 \ V, E^0_{Cu^{2+}/Cu} = +0.34 \ V, E^0_{Mg^{2+}/Mg} = -2.37 \ V$. With increasing voltage,the sequence of deposition of metals on the cathode will be:

• A
  $Ag, Hg, Cu, Mg$
• B
  $Mg, Cu, Hg, Ag$
• C
  $Ag, Hg, Cu$
• D
  $Cu, Hg, Ag$