Answer:
The Big Three were Great Britain, the United States, and the Soviet Union. The Soviet Union made the most decisions regarding the end and what happened afterwards.
Step-by-step explanation:
Stalin was the leader of the Soviet Union. He demanded that Poland donate a small part of their land to the Soviet Union and that Poland would be allowed to decide their government. Therefore, he made the most decisions regarding the end and the US and England just conformed with the decisions because Stalin had too much power against them.