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.
