Final answer:
In Medieval Europe's social system, knights were the group who would likely take the Anglo Saxon Standard Oath of Loyalty as they served as vassals to the feudal lords, providing military service in exchange for land and protection.
Step-by-step explanation:
According to the social system of Medieval Europe, the group of people who would likely take the Anglo Saxon Standard Oath of Loyalty were the knights. In the feudal system, the nobility, or lords, granted land called fiefs to fighters, who in return owed military service and other obligations, such as loyalty. These fighters, or vassals, comprised the knights who pledged to serve their lords in exchange for land and protection. The oath of loyalty, commonly known as a pledge of fealty, was a key component in maintaining the stability of feudal relationships between lords and their vassals.
The other groups mentioned in the question played different roles within this social hierarchy. The peasants, or serfs, worked the land and owed services to the nobility, but did not typically engage in the pledges of loyalty that knights did. The clergy occupied a separate ecclesiastical hierarchy, although some high-ranking members of the Church did control lands and could act as lords. The nobility were the ones who received oaths of loyalty, rather than taking them themselves.