Starting in the 400s C. E. and for the next 600 years, monks traveled all over Europe to OA) find Christian books and relics
O B) convert people to Christianity
O C) consolidate power for the new Rome
OD) collect tribute for the church of Rome

O B) convert people to Christianity

Explanation:

Monks who moved around during this period were known as Friars and they move around to preach the word of God in Christianity by trying to convert people to Christians. The period is often referred to as the Middle Ages or Medieval period. And the spread of Christianity by monks at this time is commonly referred to as Monasticism.

Hence, in this case, the correct answer is "monks travel all over Europe to convert people to Christianity."

your answer would be (a)