Two charges, each equal to q, aer kept at `x=-a` and `x=a` on the x-axis. A particle of mass m and charge `q_0=q/2` is placed at the origin. If charge `q_0` is given a small displacement (ylt lt a) along the y-axis, the net force acting on the particle is proportional to
A. y
B. `-y`
C. `1/y`
D. `-1/y`