According to paragraph 4, what problem did traditional architectural practices create for rulers of the sixth and seventh centuries? A. It was difficult to bring the necessary people and construction materials together to replace buildings periodically. B. It was very expensive to move and house the large number of people that were now associated with the government. C. It was impractical to construct buildings large enough to house the growing numbers of people and resources. D. It was too time-consuming for rulers to supervise the construction of all the necessary buildings.