As far as the option about "low birth rate," that's very much wrong. The period from 1946 to 1964 is known as the "baby boom" period in the United States. More babies were born in America than ever before in 1946, and the high birth rates continued for a number of years. Birth rates in the late 1940s and 1950s were much higher than they had been before, especially during the very low years of the Great Depression and World War II.
Answer: Europeans brought deadly viruses and bacteria, such as smallpox, measles, typhus, and cholera, for which Native Americans had no immunity
Explanation: These diseases decreased the Native American population and caused an ecological and economical imbalance.May 13, 2019(Fzrom My history folder)