Four Point Charges, Each of the Same Magnitude, with Varying

Four point charges, each of the same magnitude, with varying signs are arranged at the corners of a square as shown. Which of the arrows labeled A, B, C, and D gives the correct direction of the net force that acts on the charge at the upper right corner?

A) A
B) B
C) C
D) D
E) The net force on that charge is zero.