Which group contains only cool colours?

Correct answer: Blue, green, violet

Blue, green, and violet are generally placed in the cool-colour group, so option B is correct. These colours often suggest water, foliage, shade, distance, calmness, and coolness. Option A contains only warm colours, while options C and D combine warm colours with a cool colour. The answer follows the standard colour-wheel convention used in elementary art education, even though individual shades can produce slightly different effects.