Answer :
The correct answer is B.
Hitler had signed a non-aggresion pact (the Molotov-Ribbentrop Pact) with the Soviet Union in 1939, right before the start of WWII.
After Germany had already suceeded on the Western front, Germany controlled France, Belgium, the Netherlands, Austria, and other territories. The nazis had also invaded some nations on the East, such as Poland or Czechoslovakia.
In 1941, the German Empire shared its Eastern border with the Soviet Union. In this same year, Hitler broke the non-aggresion pact by puting in practice the Operation Barbarossa, that consisted on launching a massive attack on the Soviet Union aiming to invade its territory.
Final answer:
The Soviet Union joined the Allies in World War II mainly because Germany broke a non-aggression pact and invaded the USSR in 1941. Hitler's increasing power in Eastern Europe and potential territorial gains were also factors.
Explanation:
The main reason the Soviet Union joined the Allies during World War II was because Germany, under the leadership of Adolf Hitler, broke a non-aggression pact and launched a massive invasion against them in 1941, known as Operation Barbarossa. This was a clear breach of the Molotov-Ribbentrop Pact, a neutrality pact signed by both countries in 1939. Hitler's increasing dominance in Eastern Europe also posed threats to the USSR, making their alliance with the Western Allies strategically beneficial. While gaining control over territories captured by Germany could have potentially been a factor, the immediate threat of invasion was more significant in driving the Soviet Union's decision to join the Allies.
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