Two Parallel-Plate Capacitors with Different Capacitance but the Same Plate

Multiple Choice

Two parallel-plate capacitors with different capacitance but the same plate separation are connected in series to a battery.Both capacitors are filled with air.The quantity that is the same for both capacitors when they are fully charged is:

A) potential difference
B) stored energy
C) energy density
D) electric field between the plates
E) charge on the positive plate