The Relatively Slow Pace of the Portuguese Conquest in Brazil

The relatively slow pace of the Portuguese conquest in Brazil, compared to the meteoric success the Spaniards enjoyed over the vast Aztec and Inca empires, can be explained by all but one of the following:

A) Spanish conquistadors went straight to the top of the imperial pyramid and made full use of their arrogance, bravado and ruthless brutality to secure control
B) The Spaniards' use of sophisticated firearms and cannons played a decisive role in combat, especially in close encounters, demonstrating the crucial role of gunpowder technology in bringing down the Aztec and Inca empires
C) Both the Aztec and Inca empires were relatively recent creations in which the hierarchical power structure was still divided and contested by enemy factions, thus allowing the Spaniards to form tactical alliances among the subject population and manipulate rival groups against each other
D) European-introduced diseases took a devastating toll among the indigenous population ahead of actual military invasion, decimating the locals and thus greatly disrupting and undermining their effectiveness in repelling the Spanish onslaught