What is the best way to keep acrylic colour uniform over a large area?

Correct answer: Prepare enough mixture beforehand

The governing concept is consistency of paint mixture. Preparing enough acrylic colour in one batch keeps the pigment, binder, and dilution ratio nearly the same throughout the large area, so the dried surface has a more uniform colour. Option B is correct. Making separate mixtures can create shade differences, while changing water or applying unmixed paint does not control colour consistency. A covered palette can also slow drying while the area is painted.