Reconcile your part C conclusion about the fields with your part A conclusion about the forces. In other words, explain intuitively how the particles can feel different fields but the same forces?

Special care would be an answer

Gravity, from the center of mass of the box, extending downward normal force, from the floor under the box, extending upward, equal to gravity push force, acting at a point on the box, extending in the direction of motion friction, acting at any point on the box directly opposite the push, extending directly opposite to the motion