One Point Charge +Q Is Placed at the Center of a Square

Multiple Choice

One point charge +Q is placed at the center of a square, and a second point charge -Q is placed at the upper-left corner of the square. It is observed that an electrostatic force of magnitude 2.0 N acts on the positive charge at the center. Now a third charge -Q is placed at the lower-left corner of the square, as shown in the figure. What is the magnitude of the net force that acts on the center charge now?

A) 0.0 N
B) 2.8 N
C) 4.0 N
D) 5.3 N