Answer:
A. Both the Soviet Union and the United States worried that the other
would build up a larger nuclear arsenal.
Explanation:
The arms race began after the end of World War II, when the former allies saw each other as a dangerous ideological rival, and not a friend. The USA already had atomic weapons and the leaders of the USSR were afraid that they would have nothing to use for defense if the USA decided to attack the USSR. The United States was afraid of the widespread increase in the authority of the USSR and the expansion of the list of countries with communist rule. It is worth saying that by this time Stalin had not abandoned the idea of world revolution. Also, disagreements on ideological grounds were felt increasingly more sharply. The impetus was the speech of Winston Churchill in Fulton. The United States began to run up its nuclear potential.
In the conditions of the Cold War, the arms race had an extremely important meaning, since at any moment a real battle could begin. Each of the countries wanted to have better military means than their opponents, so that in case of war they would have an advantage.
