Vertical strokes in poster lettering are even but horizontal strokes are uneven. Which flat-brush control is needed?

Correct answer: Adjust and hold the brush angle consistently for each stroke direction

The governing concept is flat-brush orientation and edge control. A flat brush has a broad edge that produces different widths when its angle changes. During lettering, the artist should set the brush angle for vertical and horizontal strokes, then hold that angle steadily so the edges and widths remain consistent. Changing brushes is unnecessary, continuous rotation makes control worse, and watery paint affects flow rather than correcting stroke geometry. Thus A is correct.