How Did Medieval Cities Differ from Cities in the Ancient

How did medieval cities differ from cities in the ancient world?

A) Medieval cities sprang up as centers of commerce and economic activity, whereas ancient cities emerged to meet religious, social, and political needs.
B) Medieval cities featured thick walls to defend against invading Magyars, Vikings, and Saracens, while ancient cities did not need such walled fortifications because of the peace that predominated in the Hellenistic and Roman worlds.
C) Medieval cities featured far better systems of sanitation, since medieval engineers were able to improve upon the models and systems designed by Romans and Greeks.
D) Medieval cities were usually run directly by ecclesiastical authorities, whereas cities in the Roman and Hellenistic world were controlled by emperors, senates, and despots.