It is suggested that it was
that lead to a wider range of
innovative systems of agriculture and movement of goods for trade for the Aztec.
These included raised fields constructed in lakeshores (chinampas), which allowed for
more crop harvests per year. The Aztec also moved trade goods by canoe via inland
rivers and the shoreline, and by human porters.
a) greater interdependence between cities
b) the lack of domesticated pack animals
c) advances in engineering absent in civilizations of the old world at that time
d) the possession of enslaved peoples