Answer:
Option C, encourage learning within his domains, is the right answer.
Step-by-step explanation:
Pope Leo III made Charlemagne the emperor of the Holy Roman Empire. This was done due to the ongoing situation in the city, for instance, the Pope could no longer maintain harmony in the city because of his enemies. Thus he called on Charlemagne to defend the city against the enemies. In return, he agreed to give Charlemagne the crown of the Holy Roman Empire.
After becoming the emperor, the main goal of Charlemagne was to promote learning in his kingdom. He was the one who gives more focus on learning at the time when many other rulers focused on maintaining the army.