Answer:
Due to wind and waves of water.
Step-by-step explanation:
They wonder that the ball will float back to the beach because of the wind and the waves of the water. The wind blows towards the beach which moves the water in the form of waves towards the beach so if the ball lands in the water, it will floats on the surface of water and move towards the beach with the help of wind and waves of the sea. The ball floats on the water due to its lighter weight and lower density as compared to water.