Answer:
Crushed a rebellion in Rome, is the right answer.
Step-by-step explanation:
Pope Leo III placed Charlemagne, the Frankish king on the crown of the Holy Roman Empire. The main reason for this was that the Pope was not capable to defend his rivals in the town, consequently, he urged Charlemagne to come and take charge of the town. Charlemagne on the invitation of Pope crushed a rebellion in Rome and became the emperor of the Roman Empire.