Riddle of the day : In music, you must know, there's two of me to make a whole. Though there's only two of me, three tones are needed for the whole to be

David composed a poster with the image below. which set of design elements is significant in this poster? a. form, space, and line b. color, value, and line c. space, form, and shape d. line, space, and form e. shape, form, and line