Respuesta :
The answer to that is the Soviet Union. This was actually one of the reasons as to Hitler's downfall. Soviet Union was in Russia where in the Russians had the clear advantage over Hitler's army due to the size of the Russian army and the terrain. This lead to one of the defeats of the Nazi.
Hitler's invasion of the Soviet Union in June 1941 proved that he would consistently break agreements. The correct option among all the options that are given in the question is the first option or option "a". The attack of the Soviet Union by Nazi Germany occurred on 22nd of June in the year 1941 under the code name of "Barbarossa".