The best answer in regards to the specific question appears to be A: Many small towns boomed as people came to drill wells.
C because of everything that happened to them
They attacked those countries
Answer: It joined the Church and political power, which created a strong empire.
Explanation:
In the year 800, Charlemagne was crowned Holy Roman Emperor by Pope Leo III in recognition of his service to the Papacy including restoring the Pope to the Vatican after the revolt of some Roman Nobles.
The Pope saw this as an opportunity to be protected and for the Church to be powerful once more and so when he proclaimed Charlemagne as emperor, he essentially joined the church with political power which gave the empire a degree of legitimacy it did not have before and established it as a strong empire.