The correct answer is D.
The diagram describes how feudalism emerged and spread in medieval Europe, after the fall of the Roman Empire.
Feudalism was based on the existence of three states of the Realm, a system of social classes with almost no mobility among them . The First and Second States comprised the aristocracy and the clergy, who were the land propietors who had enough power to maintain armies to defend their territories.
The Third State was comprised by peasants, craftmen and local traders, in general, by the majority of the population who were too humble to own land or to defend themselves. They depend entirely on the lands of their lords, that they were allowed to cultivate for a living in exchange for heavy taxes and also dependent on their protection for survival.
