To move both balls so that they experience an equal change in motion, Olivia should use Newton's second law of motion, which states that the acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass (F = ma).
If Olivia pushes both balls with the same force (option C), the ball with less mass will experience a greater acceleration compared to the ball with more mass. Therefore, they will not experience an equal change in motion.
If she uses a greater force on the ball with more mass (option A), it will still not result in equal changes in motion due to the difference in mass.
If she pushes the ball with more mass with a lesser force than the ball with less mass (option B), the ball with less mass will still accelerate more, resulting again in unequal changes in motion.
Therefore, the correct choice is:
D. None of the above.
To achieve equal changes in motion considering both mass and force, Olivia would need to apply different forces proportionally to the masses of the balls.