Answer:
European diseases killed many people in the Americas.
Step-by-step explanation:
The Europeans were able to gain dominance over the Americas in the late 1400s and early 1500s because European diseases killed many people in the Americas.
These diseases were smallpox, measles, and the flu (influenza) because the Europeans had already developed immunity to them but the people in the Americas died in large numbers as the diseases were new to them.