What Was True About the Nonaggression Pact Stalin Signed with Hitler

What was true about the nonaggression pact Stalin signed with Hitler in 1939?

A) It divided control of Austria between Germany and the Soviet Union.
B) It was the first step to an enduring alliance between Germany and the Soviet Union.
C) It facilitated Germany's invasion of Czechoslovakia.
D) It brought the United States into the war.
E) It was Stalin's strategy for keeping Germany from invading Russia.