D. All of these choices are correct.
A is correct because Nixon tried to pull American troops from Vietnam though it took him awhile. B is correct because containment was one of the main factors of the Truman Doctrine. C is correct because Eisenhower was president during WWII when the country focused on military and economic strength.
Answer: the English, French, and Spanish explorers came to North America, they brought tremendous changes to American Indian tribes Diseases like smallpox, measles, influenza,and even chicken pox proved deadly to American Indians influenza.
Explanation:Europeans were used to these diseases, but Indian people had no resistance to them.
