In this case, equipotential surface is a straight line having slope 2,
We know that at any point on equipotential surface, electric field should be perpendicular to the equipotential surface.
(1,2) lies on our equipotential surface therefore field at this point should be perpendicular to the equipotential surface.
Hence our electric field will in the direction of line having slope (−1/2)
our our field should make an angle arctan(−1/2) with x- axis
which is true only in option (D) therefore option (D) is correct