Final answer:
Friction opposes the motion of an object and slows it down; thus, when a student moves from Step 1 to Step 3, friction would slow their movement.
Step-by-step explanation:
Friction affects the downward movement of an object by opposing the motion and causing it to slow down. Specifically, in the context of the student moving from Step 1 to Step 3, friction slows the movement rather than increasing the downward force, changing the direction of gravity, or increasing the mass of the student. When an object is sliding down an incline, the force of gravity has a component that acts downwards along the slope, and friction provides a force that opposes this component of gravity. As a result, the net acceleration of the object down the incline is reduced by the force of friction.
In summary, the correct answer to how friction affects the downward movement is: A. Friction slows the movement.