Which of the Following Is True About the Ancient Chacoan

Which of the following is true about the ancient Chacoan road system?

A) Although once thought to be an extensive network of roads, aerial photography has shown the roads to be much less extensive than initially believed.
B) Although once thought to be an extensive network of roads, aerial photography has shown that they were not roads, but were in fact part of a vast canal system.
C) It was an elaborate and extensive network of roads, covering more than 250,000 square kilometers within New Mexico, Arizona, Colorado, and Utah.
D) We now know that they were built strictly for economic purposes, to move goods to markets in Chaco Canyon.