Both dry brush and scumbling use little paint, but where does their difference mainly lie?

Correct answer: In stroke movement and intended surface effect

Both methods control the amount of paint, but their visible results depend on movement and purpose. Dry brush commonly produces broken, directional or linear marks because a nearly dry brush catches the surface texture. Scumbling generally creates a more irregular, broken veil over an underlying layer. Hence option A is correct; colour name, handle length and paper size are not the main distinctions.