The Reaction, Shown Below, That Occurs in a Hydrogen Fuel

The reaction, shown below, that occurs in a hydrogen fuel cell is exothermic.According to the conservation of energy, the reverse reaction (the electrolysis of water) 2 H₂ + O₂ → 2 H₂O hydrogen fuel cell
2 H₂O → 2 H₂ + O₂ electrolysis of water

A) is also exothermic.
B) is endothermic.
C) does not involve energy.
D) has an energy change of zero.
E) involves energy in some way, but it is impossible to determine how.