The correct statement is:
The net force causes a decrease in acceleration because without the force the ball's velocity would remain the same.
This statement reflects Newton's first law of motion, which states that an object in motion will stay in motion at constant velocity unless acted upon by a net external force. In this scenario, since a nonzero net force is acting on the moving ball, it results in a change of velocity (deceleration) leading to the ball coming to a stop.