What Are the Three Elements of Great Importance in Ecological

What are the three elements of great importance in ecological models of early state development?

A) Large population densities, large food surpluses, and diversified farming economies.
B) Diversified farming economies, irrigation agriculture, and control of trade routes.
C) Irrigation agriculture, large population densities, and diversified farming economies.
D) Large food surpluses, diversified farming economies, and irrigation agriculture.