Which of the following best describes the function of the highlighted sentence in the context of the passage as a whole? A. It provides an example of the kind of problems that often complicate investigations into environmental change. B. It calls into question the reliability of the established dates for later Holocene agricultural development. C. It describes the nature of localized agricultural developments during the later Holocene. D. It outlines a hypothesis that draws on evidence discussed earlier in the passage. E. It limits the scope of a particular complication mentioned earlier in the passage.