Answer:
The Lord:
Role - keep order and to provide protection for their vassals
Responsibilities - manage and defend his land and the people who worked it
Rights - right of jurisdiction, which gave judicial power to the nobles and lords and the right of hunting
The Knight:
Role - protecting the king
Responsibilities - protecting the king from danger or fighting in a battle
Rights - when they successfully have taken a town, they had the permission to ransack and pillage the town and keep all valuables that they had found
The Serf:
Role - peasant farmers
Responsibilities - perform labor services for his lord
Rights - protection, justice, and the right to farm certain fields within the property to earn their livelihood