The Indian Constitution is known for its key features that shape the structure of the government and rights of its citizens. Option 1, "Quasi Federal," is a correct key feature as it describes the nature of the Indian federal system, which combines aspects of both federalism and unitary government. Option 2, "Separation of Powers," is also a key feature present in the Indian Constitution, ensuring a balance of power among the legislative, executive, and judicial branches.

Option 3, "Fundamental Rights," is another key feature of the Indian Constitution. It provides citizens with certain basic rights and freedoms.

Option 4, "Aristocracy," is incorrect as it is not a key feature of the Indian Constitution. Aristocracy refers to a system of government ruled by a hereditary or privileged elite, which is not present in the Indian system.

Therefore, the correct answer is option 4.