Answer:
Color and movement
Step-by-step explanation:
This piece is "Symphony in Blue and Pink" (1868), from american painter James McNeill Whistler.
To underline his disengagement from art that conveyed ideas, Whistler often created works whose titles were borrowed from music. In doing so, it revealed its affiliation with the theory of "art for art's sake," which valued music for its aspect, let's say more abstract. Thus, his river scenes were "Nocturne"; his portraits, "Symphonies" "Harmonies"; and the portraits dominated by black and gray, "Arrangements." In choosing the title, he almost always favored the color scheme over the theme.