What kingdom was charlemagne ruler of and what is he famous for?

Charlemagne also known as Charles the Great, was a medieval emperor who ruled much of Western Europe from 768 to 814. In 771, Charlemagne became king of the Franks, a Germanic tribe in present-day Belgium, France, Luxembourg, the Netherlands and western Germany. He embarked on a mission to unite all Germanic peoples into one kingdom, and convert his subjects to Christianity. A skilled military strategist, he spent much of his reign engaged in warfare in order to accomplish his goals. In 800, Pope Leo III (750-816) crowned Charlemagne emperor of the Romans. In this role, he encouraged the Carolingian Renaissance, a cultural and intellectual revival in Europe. When he died in 814, Charlemagne’s empire encompassed much of Western Europe, and he had also ensured the survival of Christianity in the West. Today, Charlemagne is referred to by some as the father of Europe.

I’m pretty sure that the answer is b.