How was the idea of christendom instrumental in improving charlemagne's reign?

a.)christendom established self-sustaining monasteries during the reign of charlemagne, which reduced the need for direct rule.

b.)the catholic church provided charlemagne with educated clergymen to advise him in governmental policies.

c.)the catholic church insisted on a separation of church and state, which enabled the carolingian empire to expand through military conquest.

d.)christendom provided social services to knights to reduced daily concerns and provide additional training.