The Electric Potential Inside a Charged Solid Spherical Conductor in Equilibrium

The electric potential inside a charged solid spherical conductor in equilibrium:

A) is always zero.
B) is constant and equal to its value at the surface.
C) decreases from its value at the surface to a value of zero at the centre.
D) increases from its value at the surface to a value at the centre that is a multiple of the potential at the surface.
E) is equal to the charge passing through the surface per unit time divided by the resistance.