Calculate the Electrostatic Potential Energy in Joules of the Interaction $-5.1 \times 10^{-19} \mathrm{~J}$

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

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