When a charged conductor reaches electrostatic equilibrium, which is right?
选项：

A:On the surface of the conductor, the potential is higher at points where the charge density is higher.;
B:The potential is higher at points where the curvature of conductor surface is larger.;
C:The potential inside the conductor is higher than that on its surface.;
D:The potential difference between any point inside the conductor and any point on the surface is equal to zero.