Point Charges of 4 $\times$ 10^-8 C and -2 $\times$ 10^-8 C Are Placed 12 Cm Apart

Multiple Choice

Point charges of 4.0 $\times$ 10^-8 C and -2.0 $\times$ 10^-8 C are placed 12 cm apart.A third point charge of 3.0 $\times$ 10^-8 C halfway between the first two point charges experiences a force of magnitude

A) 4.5 $\times$ 10^-3 N
B) 2.0 $\times$ 10^-3 N
C) 1.5 $\times$ 10^-3 N
D) zero
E) 5.0 $\times$ 10^-3 N