I believe the correct answer is D. The four figures standing on the beach.
Whistler isn't interested in these four figures as persons with their stories - so we can't see either their experience or memories. As a symbolist, he is primarily interested in the composition and general meaning of the piece. They are faceless and impersonal. All we can see is their outfit inspired by traditional Japanese clothes, which makes them even more of a symbol. It's not even about the arrangement of the women - they are symmetrical because it suits the composer's vision, but the symmetry is not the subject matter.
