Explanation

(c)
${CuSO}_{4}\ \rightleftharpoons \ {Cu}^{2 +} + \ {SO}_{4}^{2 -}$
At cathode ${Cu}^{2 +}(aq) + \ {2e}^{-}\ \longrightarrow Cu(s)$
At anode ${2H}_{2}O(l) \longrightarrow \ O_{2}(g) + \ {4H}^{+}(aq) + \ {4e}^{-}$
Thus, for the production of one mole of copper from copper sulphate 2F of electricity is required.