3. Positive or negative charges, of equal magnitude, may be placed at the vertices of an A equilateral triangle, labeled A, B, and C. Which of the following charge placements . will result in an electric eld pointing in the y direction at the center of the triangle? 1. q at A, +q at B and C. X II. q at A, B, and C. 111. +q at A, q at B and C. (.3 1% (1) III only (2) II and III only (3) I and II only (4) I only (5) Neither I, II, or