The appropriate response is Mound Builders. The different societies by and large named Mound Builders were occupants of North America who, amid a 5,000-year time frame, developed different styles of earthen hills for religious and formal, entombment, and world class private purposes.
The answer to go in the blank would be ''river'' because the river was very vast and it was useful for many functions, so the English wanted to claim it.
B. and E. marked the downfall of the Inca empire, for obvious reasons. Disease and civil war would obviously kill the empire, and taking an important leader would also mark great chaos within the empire. A. and C. are not to be ignored however, considering that maintaining peaceful relationships with the Spaniards only brought death and chaos to the Aztecs, all from the Spaniards.