This is a multiple choice question, so try including the possible answers as well.
C
The Moroccan invasions led to the downfall of both
The correct answer is "Charlemagne crowned Holy Roman emperor, 800 CE."
The event that belongs in place C on the timeline is "Charlemagne crowned Holy Roman emperor, 800 CE."
In one of the most important events of that time, the pope Leo III crowned Charlemagne as the New Emperor of the Roman Empire. The exact date, December 25, 800 CE. Charlemagne was the King of the Frankish and was the one who could exert the leadership and influence to calm down the situation in Rome. One of the first things Charlemagne did was to improve the education conditions in the Empire.