Final answer:
The best characterization of the system depicted in the source is that feudalism revolves around mutual obligations between a lord and vassal, emphasizing loyalty in exchange for protection and land-grants. These reciprocal duties extended throughout the hierarchical structure of medieval society.
Step-by-step explanation:
The statement that best describes the system described in the source could be paraphrased as: Feudalism is based on a reciprocal relationship between the lord and the vassal where each owes certain obligations to the other. The source from Fulbert of Chartres highlights this symbiotic relationship where loyalty is exchanged for protection and the granting of land, known as a fief, in the feudal hierarchy. Both parties are expected to maintain this mutual respect and service, creating a structured social order in medieval society.
The feudal system was constructed on layers of obligations where lords provided land to their vassals for their service, especially the military. The lords, in turn, had obligations to their king, while the vassals were responsible for maintaining the land and providing wealth derived mainly from serfs or peasants. This interconnected network of loyalty and service defined feudal societies during the Middle Ages and was critical to the social and political organization of that era.