Four charges of `1mC,2mC,3mC` and `-6mC` are placed one at each corner of the square of side `1m`.The square lies in the `x-y` plane with its centre at the origin
A. The electric potential is zero at the origin
B. the electric potential is zero everywhere along the x-axis only on the sides of the square which are parallel to y-axis
C. the electric potential is zero everywhere along the z-axis for any oritentation of the square in the x-y plane.
D. The electric potential is not zero along the z-axis except at the origin
