Answer:
Correct answers are
C. He helped spread Christianity.
D. He encouraged the creation of schools.
Step-by-step explanation:
Option A is not correct as we cannot conclude that from the passage and also it is not a historical fact, as after his death there were wars the spread across Europe.
B is also not correct as he had good relations with the Papal State.
C is correct as the role of Christianity became even more important then ever. Charlemagne was the Emperor of The Holy Roman Empire.
D is also correct as development of knowledge and spreading of education finally happened during his reign.