A point charge +2Q is fixed at x = −d, and a point charge −Q is fixed at x = +d on the x–axis. Consider three observation points: A at the origin (0, 0), B at (0, 2d), and C at (2d, 0). Rank the magnitudes of the net electric field at these points from greatest to least.
a) C > A > B
b) B > A > C
c) A > C > B
d) A > B > C