Why did President Harry Truman order the Atomic Energy Commission to produce a hydrogen bomb?

A. Truman did not believe the Soviet Union could develop an atomic bomb.
B. Truman wanted to begin a perpetual arms race with the Soviet Union.
C. Truman planned to destroy the Soviet Union with B-29s dropping H-bombs.
D. Truman hoped it would restore the United States' advantage over the Soviet Union.

D. Truman hoped it would restore the United States' advantage over the Soviet Union.