Which of the following is a true statement about Spanish exploration in the Americas?
A. Columbus was fully aware that he had encountered two continents previously unknown to Europeans.
B. Amerigo Vespucci was the first European to contend that Columbus had encountered two continents previously unknown to Europeans.
C. Conquistadors were mainly interested in studying the Americas and befriending the native peoples.
D. Native illnesses wiped out over three-fourths of the conquistadors who came to the Americas.