The electric potential at the surface of a charged conductor .

A. is always zero. is always independent of the magnitude of the charge on the surface.
B. is always such that the potential is zero at all points inside the conductor.
C. may be set equal to zero by adding an appropriate constant to the potential at all points of space.
D. is always such that the potential is always zero within a hollow space inside the conductor.

The electric potential at the surface of a charged conductor is always such that the potential is zero at all points inside the conductor.

Explanation:

Each point on the surface of a balanced charged conductor has the same electrical potential.

The surface on any charged conductor in electrostatic equilibrium is an equipotential surface. Since the electric field is equal to zero inside the conductor, the electric potential at any point inside and on the surface is equivalent to its value.