Answer:
B.Vassals.
Feudalism was the system in 10th-13th century European medieval societies where a social hierarchy was established based on local administrative control and the distribution of land into units (fiefs). A landowner (lord) gave a fief, along with a promise of military and legal protection, in return for a payment of some kind from the person who received it (vassal).
The payment of the vassal to the lord typically came in the form of feudal service which could mean military service or the regular payment of produce or money. Both lord and vassal were freemen and the term feudalism is not generally applied to the relationship between the unfree peasantry (serfs or villeins) and the person of higher social rank on whose land they laboured.