Two Infinite,uniformly Charged,flat Surfaces Are Mutually Perpendicular

Multiple Choice

Two infinite,uniformly charged,flat surfaces are mutually perpendicular.One of the sheets has a charge density of + 20.0 pC/m²,and the other carries a charge density of -50.0 pC/m².What is the magnitude of the electric field at any point not on either surface?

A) 2.75 N/C
B) 2.82 N/C
C) 3.04 N/C
D) 3.37 N/C
E) 4.45 N/C