Prevent communism from spreading even further in Asia.
Communist troop sanctuaries were located in Cambodia, Nixon fearing the worse for the spread of communism as the Cold War was still in motion. Nixon assumed that the Viet Cong was using bases in Cambodia to attack the American's and South Vietnamese people during the Vietnam war.
Hope this helps!
China. I remember learning about that a few years ago.
I'm gonna say C. the Proclamation Line of 1763
Greek theter helped to inspire modern drama. Also the famous philosphers like Plato, Aristotle, Epictetus, and Epicurus. They also helped influence the english alphabet. Let me know if yiou need need more.