What is the technique of creating thick raised texture with acrylic colour called?

Correct answer: Impasto

Impasto is a painting technique in which pigment is applied in thick, visible layers so that the surface develops raised texture and expressive marks. Option D is correct because the defining feature is the physical thickness of the paint, not merely a change in colour. A wash uses diluted, thin paint; stippling builds texture with dots; and blending softens transitions between colours. Those techniques may appear in the same artwork but do not specifically mean thick raised application.