A. He captured Moscow but then had to retreat with terrible losses
The city of Moscow was deliberately incinerated by the Russian forces that would never by any means surrender. In the midst of a cruel winter, the French armies found a city that had no provisions, left abandoned and with a campaign that had last long. Tactically Napoleon was defeated by the unsustainability of trying to set on the ruins of a devastated city, in just 6 weeks he left back to France with the remaining and surviving French Armee.
Napoleon ordered the armies to return and retreat, however, only a 10th percent of his army from an estimated 400 000 remained alive and survived later on. This is also a major turning point in history.