As Shown in the Figure, a Square Insulating Slab 5

As shown in the figure, a square insulating slab 5.0 mm thick measuring 2.0 m × 2.0 m has a charge of 8.0 × 10^-11 C distributed uniformly throughout its volume. Use Gauss's law to determine the electric field at point P, which is located within the slab beneath its center, 1.0 mm from one of the faces.

A) 0.68 N/C
B) 14 N/C
C) 23 N/C
D) 34 N/C
E) 57 N/C