The developments under charlemagne are sometimes referred to as the "carolingian renaissance." which of the following describes those changes?

an increase in literacy, advancement of the arts, and improvements in the legal system
a revival of polytheism, roman government, and roman construction
an increase in the authority of the church, the state, and the serfs
monarchs acquired the power to name bishops, dukes, and knights.

An increase in literacy, advancement of the arts, and improvements in the legal system

The Carolingian Renaissance was a significant renewal of Western culture during the Middle Ages, after the Charlemagne's order to bring the greatest scholars of his time to his court and to teach a small group, called the intellectuals. In this Renaissance, there was a new uplift in the fields of art, literacy, architecture, philosophical writings, and quality of church music that still remains nowadays.

Likewise, as a ruler who had supreme jurisdiction in judicial matters, Charlemagne made legislation, led the army, and protected both the church and the poor, and attempted to organize the kingdom, church, and nobility around him to better control it.