What should be done to make foreground grass appear clearer in a painting?

Correct answer: Some dark and distinct diagonal strokes should be applied

The governing concept is depth through contrast and selective detail. Foreground objects are made clearer by using stronger values, more defined marks, and visible directional structure. Applying some dark, distinct diagonal strokes suggests individual blades and increases the sense of nearness, so option D is correct. Erasing marks or using only water removes definition, while directionless strokes do not convincingly describe the growth pattern of grass.