A combination of capacitors is set up as shown in the figure. The magnitude of the electric field, due to a point charge Q (having a charge equal to the sum of the charges on the `4 mu F` and `9 mu F` capacitors), at a point distance 30 m from it, would equal:
A. `360 N//C`
B. `420 N//C`
C. `480 N//C`
D. `240 N//C`