Answer:
C. the Holy Roman Empire
Step-by-step explanation:
Following the crowning of Charlemagne otherwise known as Charles the Great, as the Emperor by Pope Leo III on 25th December 800 AD. He was made the King of the Franks, Emperor of the Holy Roman Empire.
His reign and sovereignty cover a large part of Europe including places like France, Germany, and the other smaller surrounding countries.
Hence, in this case, the correct answer is "the Holy Roman Empire."