The correct option is
B Ag will reduces
Cu2+ to Cu
Reduction potential is given as:
E0Ag+/Ag = +0.80 V ; E0Cu2+/Cu = +0.34 V, E0Fe3+/Fe2+ = +0.76V; E0Ce4+/Ce3+ = + 1.60 V
Thus the increasing order of reduction potential is:
Cu2+<Fe3+<Ag+<Ce4+
possible reactions are:
Cu+Mn+→Cu2++M where Mn+=Fe3+,Ag+,Ce4+
Fe+Mn+→Fe2++M where Mn+=Ag+,Ce4+
thus higher the reduction potential more the tendency to get reduced.
A. Fe reduces Ce4+ to Ce3+ and itself gets oxidised to Fe2+ but does not oxidise Ce3+.
B. Cu metal can reduce Fe3+,Ag+,Ce4+ ions into Fe, Ag and Ce, respectively.
C. Ag will not reduce Cu2+ to Cu as its reduction tendency is higher than Cu2+
D. Fe2+ can reduce Cu2+ to Cu as the oxidation potential of E0Fe2+/Fe3+ =-0.76 V is higher than E0Cu/Cu2+=-0.34 V.