The correct answer to the question is : The second law of Newton.
EXPLANATION:
As per the question, the ball is initially hit by a man.
The same ball is hit by a boy.
The ball moves faster for man than that of for the boy. It means the acceleration of ball in case of man is more as compared to the acceleration of the ball for the boy.
From Newton's second law, we know that force applied on a ball is equal to the product of mass with acceleration.
Mathematically force F = ma.
Here, m is the mass and a is the acceleration of the object.
Hence, more is the force, the more will be the acceleration.
As the ball is moving faster for man, he has applied more force on the ball.
Hence, the Newton's second law of motion accounts for the given statement.