Final answer:
The collision indicates that ball A is more massive since it bounces back while ball B moves off slowly to the right, which is consistent with conservation of momentum in a collision between two objects of differing masses.
Step-by-step explanation:
The scenario described involves a collision between two balls, A and B. To determine which ball has greater mass based on the information provided requires an understanding of the principles of conservation of momentum and kinetic energy in collisions. If ball A bounces back after the collision and ball B moves off slowly to the right, it suggests that ball A has a greater mass. This is supported by the conservation of momentum, because if ball B had been more massive and stationary, ball A would not recoil with as much velocity after the collision. Instead, a more massive ball A transfers some of its momentum to the less massive ball B, causing ball B to move off with less velocity than ball A initially had.