Identify the correct free-body diagram for a box being pushed horizontally by a person across a smooth, frictionless floor at a steadily increasingspeed.

In the diagrams, ?? represents the normal force exerted by the floor, ??push represents the force exerted by the push, ?? represents the force of gravity, ?? represents the friction force, ??? represents the mass of the box times its acceleration, and ???ext represents the sum of the external forces acting on thebox.

O O push push W WO O ma push push W W