A Hollow Conducting Sphere of Radius 12 Cm Had a Charge

A hollow conducting sphere of radius 12 cm had a charge of 18 $\mu$ C placed on it.What is the potential 20 cm from the center of the sphere?

A) 0 V
B) 15 V
C) 73 V
D) 8.1 $\times$ 10⁵ V
E) 4.1 $\times$ 10⁵ V