Option 1: Feudalism is a system where power is decentralized and based on a hierarchy of land ownership and loyalty. It does not involve the division of power between a central authority and constituent units, so it is not the correct option.
Option 2: Democracy is a system where power is held by the people and decisions are made through voting. It does not involve the division of power between a central authority and constituent units, so it is not the correct option.
Option 3: Federalism is the correct option. It is a system of government where power is divided between a central authority and various constituent units, such as states or provinces. It allows both levels of government to have their own jurisdiction and makes decisions through a combination of centralized and decentralized power.
Option 4: Aristocracy is a system of government where power is held by the nobility or a privileged ruling class. It does not involve the division of power between a central authority and constituent units, so it is not the correct option.
Therefore, option 3, Federalism, is the correct answer.