A body 'A' experiences perfectly elastic collision with a stationary body 'B'. If after collision the bodies fly apart in opposite directions with equal velocities , the mass ratio of 'A' and 'B' is

Question

$$\begin {array} {1 1} (a)\;\frac{1}{2} & \quad (b)\;\frac{1}{3} \\ (c)\;\frac{1}{4} & \quad  (d)\;\frac{1}{5} \end {array}$$