In paragraph 5, the author indicates that twentieth century art has shown that naturalism does not necessarily follow abstraction in some kind of predetermined sequence in order to A. emphasize that it may not be possible to determine what the figures in ancient rock art represent B. suggest a reply to those who have questioned Maynard's interpretation of the sequence of Australian rock art C. provide a counterexample to Maynard's interpretation of the sequence of Australian rock art D. indicate that twentieth century art is more advanced than ancient rock art