A Parallel Plate Capacitor, Filled with Air, Has Circular Plates

A parallel plate capacitor, filled with air, has circular plates with a separation gap of 1.5 mm. If it is desired to store 12 mJ in this capacitor, what must the plate area be for a voltage of 1.5 kV?

A) 1.10 m²
B) 0.55 m²
C) 0.90 m²
D) 1.8 m²