Which one of the following determines that the Indian Constitution is Federal?

The defining feature that makes the Indian Constitution federal is the constitutional division of powers between the Centre and the States. Federal systems are characterized by two levels of government with their powers allocated by a written constitution; the Indian Constitution satisfies this essential condition by establishing dual government and explicitly distributing legislative subjects between Union, State and Concurrent lists [1]. While other attributes—such as a written or rigid constitution and an independent judiciary—support federalism, they are supplementary. The three-fold distribution of legislative powers and the supremacy of the Constitution as the source of authority underpin India’s federal character, as reflected in the allocation of subjects and the role of courts in adjudicating Centre–State disputes [3].

Sources

1. [1] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 16: India–Political Aspects > Geographical Bases of India Federalism > p. 10
2. [2] Indian Polity, M. Laxmikanth(7th ed.) > Chapter 4: Salient Features of the Constitution > 4. Federal System with Unitary Bias > p. 29
3. [3] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 16: India–Political Aspects > STRUCTURE OF INDIAN FEDERATION > p. 11