The standard electrode potentials E M + / M o of four metals A,   B,   C and D are − 1 .2…

In complete cation electrolysis at cathode, the species having higher reduction potential is preferably reduced at cathode
${\text{E}}_{\text{C}}^{\circ }>{\text{E}}_{\text{B}}^{\circ }>{\text{E}}_{\text{D}}^{\circ }>{\text{E}}_{\text{A}}^{\circ }$
Hence,  $\mathrm{C} > \mathrm{B} > \mathrm{D} > \mathrm{A}$
will be the preference of deposition of these metals on competing.