Answer:
Distance and harsh winters disrupted German supply lines.
Explanation:
October 1941 was the worst month because it was cold as it had not been for years, the Germans were out of winter clothing because the Fürher refused to send in his winter clothes, trusting that his army would conquer Moscow in time. Whatever the winter (and distance) did damage in the German army and even though some advanced units came to enter the suburbs of the city the invasion stopped.
Rigorous winter was fundamental for the Soviet resistance, since thus Stalin removed the Siberian troops and sent them to the front in Moscow. New troops, trained and equipped for the winter war against ill-equipped Germans who were dying of cold. A counter-offensive was launched that cost a lot of lives and material for both sides, yet the Germans had to withdraw more than 100 kilometers from Moscow.