The equation for electric potential of a point charge is:
V=(k*q)/r where k=9*10^11 N m²/C², q is the charge and r is the distance from the charge to the point in which we are calculating the potential.
q=-5.2*10^-6 C
r=12 cm = 0.12 m
Now we plug in the numbers and get:
V=-3.9*10^5 Volts, so the correct answer is the second one.
