The fourth power of each proposal has an argument (angle multiplied by 4) : A. 320*4 = 1280° = 3*360 + 200° is NOT suitable : NO C. 60*4 = 240° is NOT suitable : NO D. 280*4 = 1120° = 3*360 + 40° is NOT suitable : NO and finally : B. 30*4 = 120° is suitable : YES : ONLY suitable answer