Which of the Following Statements About Pre-Columbian Civilizations Is True

Which of the following statements about pre-Columbian civilizations is true?

A) Most of these civilizations were based on broad networks of trade.
B) Only the Incas and Maya built sophisticated and complex cities and urban societies.
C) Economies based on agriculture allowed extended settlement in one area and the development of a broad trade network.
D) Most of these societies had been decimated by internal wars even before Europeans arrived.
E) Several of their great cities probably reached populations of about one quarter of a million residents each.