Which two contrasts increase the power of a small red dot in a vast green field?

Correct answer: Complementary colour and quantity contrast

The governing concept is combined contrast. Red and green are complementary hues, so their opposition makes the dot visually vivid. The very small red area against a vast green area also creates quantity or area contrast, increasing emphasis through rarity. Thus B is correct. The question does not establish a texture, direction, symmetry, or value difference strong enough to make the other pairs the best answer.