Velocity after Elastic Collision!

Classical Mechanics Level 4

Two steel spheres, having radii $a$ and $2a$ are released from a height $h$ as shown in figure. Assume that during motion the centers of the spheres lies on a vertical line. Larger sphere collides with the ground and recoils and collides with the small sphere. Collisions are perfectly elastic. Velocity of small sphere just after its collision is-

\frac{9}{23} \sqrt{2g(h-2a)}

\frac{23}{9} \sqrt{2g(h-2a)}

\frac{5}{9} \sqrt{2g(h-2a)}

None of These

\frac{9}{5} \sqrt{2g(h-2a)}