Two Particles Have Charges Q and -Q (Equal Magnitude and Opposite

Two particles have charges Q and -Q (equal magnitude and opposite sign) .For a net force of zero to be exerted on a third charge it must be placed:

A) midway between Q and -Q
B) on the perpendicular bisector of the line joining Q and -Q, but not on that line itself
C) on the line joining Q and -Q, to the side of Q opposite -Q
D) on the line joining Q and -Q, to the side of -Q opposite Q
E) at none of these places (there is no place)