Which background can effectively highlight a red title in a poster?

Correct answer: Green background

The governing design concept is complementary contrast. Green lies opposite red on the traditional colour wheel, so the two hues create strong visual separation when used with suitable differences in value and intensity. Therefore, option B is correct. Orange and pink are related to red and may reduce separation, while a red background provides little hue contrast and can make the title difficult to read. Balance and readable lettering remain important.