A Capacitor in an LC Oscillator Has a Maximum Potential $\mu$

A capacitor in an LC oscillator has a maximum potential difference of 15 V and a maximum energy of 360 $\mu$ J. At a certain instant the energy in the capacitor is 40 $\mu$ J. At that instant what is the potential difference across the capacitor?

A) zero
B) 5 V
C) 10 V
D) 15 V
E) 20 V