The world needs a new source of energy, an unspillable source.

Which one of the reactions must be carried out in an electrolytic cell rather than in an electrochemical cell?

A.Zn2+ + Ca—Zn + Ca2+
B.Al3+ + 3Br- —Al + (3/2)Br2
C.2Al + 3Fe2+— 2Al3+ + 3Fe
D.H2 + I2(s)—2H+ + 2I-