The demographic changes in Central/South America from 400 B.C.E. to 600 C.E. can best be
explained by which of the following?
a. Mass migrations of people southward from North America
b. Diffusion of agriculture, which caused an incremental rise in population
c. Warfare between 10 c.E. and 200 c.E., which reduced the male population significantly
d. Increased interaction through trade, which led to the spread of diseases to which people
gradually developed immunities