12. A conducting sphere is charged with a total charge Q (Q ＞ 0) and in electrostatic equilibrium. Which of the following statement is true? (The electric potential at infinity is defined zero.)
(A) The potential is the lowest, but not zero, at the center of the sphere.
(B) The potential at the center of the sphere is zero.
(C) The potential at the surface is higher than the potential at the center.
(D) The potential at the center is the same as the potential at infinity.
(E) The potential at the center of the sphere is the same as the potential at the surface.