Concept:Separation of powers keeps government responsibilities divided among distinct branches.
Explanation:The legislative, executive, and judiciary are given separate functions under this principle.
Each branch exercises only its own core duties and cannot take over the core functions of another branch.
This prevents power from being concentrated in one body and limits the risk of tyranny.
It also promotes accountability through checks and balances.
The description in the question refers exactly to the doctrine of separation of powers.
It is not fusion of power, a parliamentary system, or aristocracy.
Answer:D. separation of powers