Which colour combination will have the sharpest visual contrast?

Correct answer: Red and green

Answer: B, red and green. Visual contrast means a clear difference that makes neighbouring colours stand apart. On the traditional colour wheel, red and green are complementary colours: they are placed opposite each other. Opposite colours generally produce a strong, sharp contrast when placed side by side, so the pair attracts attention. A is incorrect because blue and blue-green are neighbouring, or closely related, colours and therefore usually create a gentler difference. C is also incorrect because yellow and yellow-orange are adjacent colours, so their relationship is more harmonious than sharply contrasting. D is incorrect because grey and light grey differ mainly in value, or lightness, and the difference shown here is not as strong as the complementary contrast of red and green. The exact strength can also depend on brightness and area, but among these choices B is the clearest answer. Memory cue: opposite sides of the colour wheel usually mean strongest colour contrast.