Four Point Charges of Equal Magnitudes but with Varying Signs $d$

Four point charges of equal magnitudes but with varying signs are arranged on three of the corners and at the center of the square of side $d$ as shown in the figure. Which one of the arrows shown represents the net force acting on the center charge?

A) $\mathrm { A }$
B) $B$
C) $\mathrm { C }$
D) $D$