The correct answer is B) arms race.
The idea from the Cold War that is most similar to this scenario is the arms race.
During the Cold war years was the permanent dispute between the United States and the Soviet Union to have better nuclear weapons. Both countries wanted to have the supremacy in the production of Nuclear weapons for security and dominant reasons. The United States had the advantaged after the launch of the nuclear bombs in Hiroshima and Nagasaki to end World War II, but years after this, the Soviet Union discovered Uranium reservations in Eastern Europe and they began building nuclear weapons. The first Soviet bomb was detonated on August 29, 1949.
The other options of the question were a) Nonalignment, C) Communism, and D) Proxy wars.