What can change in a painting when the direction of brush strokes changes?

Correct answer: The effect of movement and texture

The governing concept is that brush direction is a visual mark-making technique. Horizontal, vertical, diagonal, or curved strokes can suggest different movement, energy, form, and surface texture. Therefore, changing direction changes the expressive effect of the painting, making option A correct. It does not alter the paper’s original size, the brush’s price, or the name of a colour, so B, C, and D are unrelated distractors.