The correct answer is - C. destruction of the Aztec empire by conquistadors.
The Spanish, when arrived on the Mexican mainland, saw that there's a great and strong civilization there, and that civilization, the Aztecs, were controlling big portion of the region.
In order to be able to establish their rule and get hold on to the riches of the region, the Spanish new that they would have to destroy the Aztec empire, and they did that by making alliances with the people that were under their rule, and were despising the Aztecs because of their violent rule.
The Spanish used the knowledge of the terrain of the native tribes, as well as their knowledge of the war style of the Aztecs, so the Spanish managed to defeat them with relative ease, and got hold on the region.
