During the electrolysis of copper sulphate aqueous solution using copper electrodes,the reaction taking place at the cathode is:

• A
  $Cu_{(s)} \longrightarrow Cu^{2+}_{(aq)} + 2e^-$
• B
  $Cu^{2+}_{(aq)} + 2e^- \longrightarrow Cu_{(s)}$
• C
  $H^{+}_{(aq)} + e^- \longrightarrow \frac{1}{2} H_{2(g)}$
• D
  $SO_4^{2-}{_{\text{(aq)}}} \rightarrow SO_{3\text{(g)}} + \frac{1}{2}O_{2\text{(g)}} + 2e^{-}$