According to paragraphs 3 and 4, all of the following are true of the nests of Macroternes natalensis EXCEPT: A. The walls are built out of soil mixed with termite saliva. B. The nests can be as tall as they are wide at the base. C. The interior of the nest is kept as humid as possible. D. The termites use hollow, thin-walled ridges to travel from one part of the nest to another.