Electrostatic Potential and Capacitance question for NEET (NEET 2022), with solution

Answer: (D) $90°$

No work is done moving a charge along an equipotential surface, so the field has no component along it: $\vec{E}\cdot d\vec{l} = 0$.

Electric field lines are therefore always perpendicular ($90°$) to equipotential surfaces.

Solution by Sreeraj P, M.Sc Physics