Three point charges q1 (15 C), q₂ (10 C), and q₃ (16 C) are located at (0, 0) cm, (0 cm, 3 cm), and (4 cm, 3 cm) respectively. Calculate the electrostatic potential energy of this system of charges.
a) 0.78 J
b) 1.44 J
c) 2.16 J
d) 3.24 J