Two Point Particles, with the Same Charge, Are Located at Two

Multiple Choice

Two point particles, with the same charge, are located at two vertices of an equilateral triangle.A third charged particle is placed so the electric field at the third vertex is zero.The third particle must:

A) be on the perpendicular bisector of the line joining the first two charges
B) be on the line joining the first two charges
C) be identical to the first two charges
D) have the same magnitude as the first two charges but may have a different sign
E) be at the center of the triangle