Calculate the Electrostatic Potential Energy in J of the Interaction $\times$

Calculate the electrostatic potential energy in J of the interaction of one magnesium ion (86 pm radius) and one bromide ion (182 pm radius) in magnesium bromide.

A) -5.1 $\times$ 10^-19 J
B) -1.0 $\times$ 10^-18 J
C) -1.3 $\times$ 10^-18 J
D) -8.6 $\times$ 10^-19 J
E) -1.7 $\times$ 10^-18 J