The correct answer is D. To protect against an aggressive Soviet Union in Europe.
After World War II ended, the United States and Soviet Union emerged as global superpowers. Both were set out to spread their power, influence, and ideologies to other countries. In this case, the Soviet Union was trying to spread their communist ideas to other nations. Many European countries and the United States wanted to stop communism from spreading. To do this, they formed the North Atlantic Treaty Organization (NATO). This was a political and military alliance, one that promised that each country would support each other with military help if the Soviet Union tried to invade their country.
The main things are Funions and Geography. Hope this helps!!
