Which of the following best describes the nuclear arms race between the world's two superpowers during the 20th century?
◦ the rapid efforts of world governments to arm and thereby protect Eastern European countries from attack by the Soviet Union in the wake of World War II
◦ a tense relationship between the United States and the Soviet Union in the 1950s and 1960s, during which each side was intent on procuring more weapons than the other
◦ the U.S. and Soviet race in the early twenty-first century to prevent the spread of weapons of mass destruction to unstable governments
◦ the efforts to rapidly reduce the number of nuclear weapons held by the United States and the Soviet Union