The correct answer is A. Exposure to diseases like smallpox
Explanation:
From the 15th century to the 18th century Europeans from different countries including England, Spain, and Portugal arrived at different zones of America with the purpose of colonizing them; however, in the territory, there were multiple indigenous tribes and groups that had lived in America during centuries before the European arrival. Because of this, native population faced multiple conflicts and issues with the arrival of colonizers, one of the major issues this population experienced and that led to population decline were the diseases Europeans brought with them including smallpox and measles. These diseases that were very common in Europe killed an important percentage of the population because native people had never been exposed to them and therefore their immune system did not have a positive response to them, indeed these killed more indigenous people than wars, slavery and other issues. Therefore, the most deadly threat to indigenous Americans was the exposure to diseases like smallpox.
