A point charge Q1=+5.6μC is fixed in space, while a point charge Q2=+2.1nC, with mass 6.3μg, is free to move nearby. Calculate the electric potential energy of the system. Which of the following options correctly represents the calculation of the electric potential energy?

A) Q1 * Q2
B) Q1 / Q2
C) Q1 + Q2
D) Q1 - Q2