By the early 1500s, Spain had developed a foothold in the New World. In a period of fewer than four decades following Columbus's first voyage of discovery, the Spanish defeated both the Aztec and Incas empires. Which of the following best illustrates the primary factor that led to the collapse of the Aztec and Inca empires?
a) Advanced weaponry and tactics
b) Introduction of new diseases
c) Famine and drought
d) Betrayal by local rulers
