What Made It So Difficult for the United States to Reject

What made it so difficult for the United States to reject the demands of Joseph Stalin for establishing a Soviet sphere in eastern Europe?

A) Roosevelt realized the sacrifices the Soviets had made in their victory in the Eastern front.
B) The Soviet Union had long feared the aggressive governments of eastern Europe.
C) It was hard for Roosevelt to distinguish between eastern European Slavs and Russian-speaking Soviets.
D) Since the United States wanted to create a similar sphere of influence in western Europe, Stalin's request could hardly be denied.
E) Virtually all of the eastern European territories in question had once been part of the Russian empire.