For an electric dipole, the equipotential surface having zero potential is
A spherical surface with its centre at the centre of the dipole
The surface of an ellipsoid with its centre at the centre of the dipole
The surface of a paraboloid
A plane surface passing through the centre of the dipole and perpendicular to the axis of thedipole
For the dipole shown in figure, potential at any point on the line MN is zero.