Two boxes, one more massive than the other, rest in contact with one another on a smooth, level floor. A horizontal force F pushes on one or the other of the boxes. Which statement most accurately describes the contact force between the boxes?
A. It is larger when F is applied to the more massive box.
B. It is larger when F is applied to the less massive box.
C. It is equal no matter which box it is applied to.
D. It can be larger or smaller depending on the actual masses of the boxes.