What should be changed to create a light-to-dark effect in a graded wash?

Correct answer: Ratio of pigment and water

The governing concept is value control through dilution. To begin a graded wash lightly, use more water and less pigment; as the wash progresses, increase pigment concentration or reduce the amount of water so the value becomes gradually darker. Therefore B is correct. Paper size, the brush’s name, and the palette’s colour do not directly control the light-to-dark value change. The transition should remain gradual rather than abrupt.