Why can an electric field line not be parallel to an equipotential surface at a point?
Correct answer: A
An equipotential surface has the same potential at every point, so the tangential change in potential along that surface is zero. Since the electric field is E = −∇V, it has no tangential component there and must be normal, or perpendicular, to the surface. If a field line were parallel, it would imply a potential decrease along the surface, contradicting its equipotential definition. Hence A is correct; the other statements confuse geometry or incorrectly claim the field vanishes.