Which method is useful for making colour rhythm clearer in a picture?

Correct answer: Repeating a fixed colour sequence

Colour rhythm is a form of visual rhythm in which hues or colour groups recur in an organized pattern. Repeating a fixed sequence, such as blue-yellow-red-blue-yellow-red, gives the eye a predictable visual beat and makes the relationship clear. Therefore option B is correct. Random placement removes the sequence, turning all colours grey reduces colour variety, and using a colour only once provides no repetition for rhythm.