FIGURE 21-4 -Four Point Charges of Equal Magnitude and Varying Signs Are

FIGURE 21-4
-Four point charges of equal magnitude and varying signs are arranged on corners of the square of side d as shown in Fig. 21-4. Which of the arrows shown represents the net force acting on the charge at the upper right hand corner of the square?

A) A
B) B
C) C
D) D
E) none of the above