Answer:
C. When the Europeans introduced small pox, measles, typhus, and other diseases to the New World.
Step-by-step explanation:
The introduction of new diseases was one of the most devastating consequences of the discovery of America and the subsequent colonization of native people. Europeans who travelled to America often carried pathogens that did not exist in this continent. Because of this, Americans had no immunity against them. Therefore, they died in very large numbers or got gravely sick. This weakened the people and their social structures, making it easier for the Europeans to conquer them.