After world war ii, the soviet union maintained control of many eastern european nations mainly because these nations were extensions of communist power can you explain why this is the answer?

The answer is indeed a confusing one, and seems incomplete. However, the during WWII, the Soviet Union invaded Eastern Europe and took it from German control. However, once the war ended, the Soviet troops that had liberated Eastern Europe maintained their occupation and kept control over the area. Their control of Eastern Europe was the extent of Communist control. 

Napoleon's Downfall and First Abdication
In 1810, Russia withdrew from the Continental System. In retaliation, Napoleon led a massive army into Russia in the summer of 1812. ... During the disastrous retreat, his army suffered continual harassment from a suddenly aggressive and merciless Russian army.Sep 27, 2019
Died: May 5, 1821
Spouse: Empress Joséphine, Marie Louise, Napoleon