Which control is most important for maintaining an even value during a large flat watercolour wash?

Correct answer: Keep mixture brush load and stroke speed consistent

The governing concept is uniform deposition during a flat wash. Keeping the paint mixture, brush load, and stroke speed consistent helps each stroke place a similar amount of pigment and water, so the value remains even. Option A is correct. Changing the water or colour between strokes creates visible shifts, while repeatedly drying the paper interrupts the wet edge and can produce bands, blooms, or hard joins.