There Are Many Fuel Cell Systems, but One of the More

There are many fuel cell systems, but one of the more commonly studied is the Hydrogen/Oxygen fuel-cell, the two half reactions of which are shown below.
Reaction A 2 H₂ + 4 OH^- -----> 4 H₂O + 4 e^-
Reaction B O₂ + 2 H₂O + 4 e^- -----> 4 OH ^-
Which reaction takes place at the cathode?

A) Reaction A
B) Reaction B
C) the reverse of Reaction A
D) the reverse of Reaction B
E) All of the above