The answer is (c): the ball will move along a path tangent to the path of the barrier at the point where the ball leaves contact with the barrier. This is shown in an mpeg video by clicking your mouse on the photograph below.

This case is really identical to that of Question 44. The inside of the tube plays no part in the dynamics, and the outside of the tube plays the same role in Question 44 as the barrier plays in this experiment.


