Which habit is useful for creating a flat even acrylic layer?

Correct answer: Move the brush with consistent direction and pressure

The governing painting principle is controlled brush application. Moving the brush in a consistent direction with fairly even pressure distributes acrylic paint uniformly and reduces unwanted streaks, making option C correct. Changing colour every stroke creates visual inconsistency, scratching wet paint damages the surface, and using unmixed paint can produce uneven pigment and thickness. A suitably consistent paint mixture and overlapping strokes also help produce a smooth flat layer.