What leader transformed the Soviet Union into a totalitarian communist state in the 1920s and 1930s?

A) Joseph Stalin
B) Leon Trotsky
C) Nikita Khrushchev
D) Gregory Zinoviev
E) Nikolai Bukarin

Joseph Stalin was the leader who transformed the Soviet Union into a totalitarian communist state in the 1920s and 1930s. He established a dictatorship and implemented policies of rapid industrialization and collectivization, which caused widespread famine and the death of millions of people through purges and forced labor camps. His regime was characterized by strict control over every aspect of society and a cult of personality around himself.