Which Statements Must Be True About the Surface of a Charged

Which statements must be true about the surface of a charged conductor in which no charge is moving? (There could be more than one correct choice.)

A) The $\vec { E }$ field is zero at the surface.
B) The electric potential of the surface is zero.
C) The $\vec { E }$ field is constant at the surface.
D) The electric potential is constant over the surface.
E) The $\vec { E }$ field is perpendicular to the surface.