How Did Stalin Change His Position Between the Meeting at Yalta

Multiple Choice

How did Stalin change his position between the meeting at Yalta in February 1945 and the meeting in Potsdam later that year?

A) He refused to permit elections in Soviet-occupied Poland.
B) He forgave Germany's war debt to Russia.
C) He gave up his demands for a Soviet-controlled section of Germany.
D) He refused to declare war on Japan.
E) He announced Russia could not afford to provide security to Eastern Europe.