According to paragraph 5, what is the possible significance of new geological field studies in Chaco? A. They indicate that during the construction boom the Chaco area probably did have enough water and sediment to attract farmers to that area. B. They could undermine the theory of Chaco as a religious center. C. They show the presence of excessive amounts of water, which may have led to the departure of most of the people living there during the Bonito phase. D. They suggest that the kind of sediment present in Chaco in the eleventh century was not favorable for agriculture.