The arms race between the united states and the soviet union began when
a) the us first launched a nuclear missile.
b) the soviet union developed its own atomic bomb.
c) the soviet union launched its first satellite.
d) nasa created the mercury program.

The correct answer here is the option B.

We can say that the arms race between the United States and the Soviet Union began when the Soviets developed their own nuclear bomb. This meant that the Cold War was getting even more serious as both sides went on to stockpile atomic weaponry and build even better weapons in order to keep the upper hand on the other side.