Answer:
Vassals is your correct answer.
Explanation:
Technically, Knights can also hold land (out of the given choices) under the feudal system, but they typically qualify as a Vassal at that rate. A Vassal received land from a Lord under the conditions that the Vassal will supply goods created from the land, but most importantly, soldiers in time of war. A Vassal was to swear allegiance to always come to his Lord's aid when the time calleth for it.
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