Which of the following is not a federal feature of the Indian Constitution?

The answer is C, Single Citizenship. India has one citizenship, that of the Indian nation, and not separate state citizenship. This is a unitary feature, which is why it is the odd one out.

Why the others are federal features:

• A: Division of powers between Union and States through the Union, State and Concurrent Lists in the Seventh Schedule (Article 246) is the core of federalism.
• B: A written, codified Constitution is a basic federal requirement, since the division of powers must be fixed in writing. India's Constitution is a written document, though it has some unwritten conventions.
• D: An independent judiciary with the power of judicial review to settle Centre-State disputes (Articles 131 and 136 to 147) is a federal safeguard.

Citizenship is dealt with in Part II (Articles 5 to 11), and Article 11 lets Parliament regulate it. Mains angle: Dr Ambedkar's description of a 'Union' with a strong Centre, and how cooperative federalism works through bodies like the GST Council.

Trap: Aspirants treat 'federal' and 'unitary' as opposites and assume India is wholly one or the other. India is a federal system with a strong unitary bias, so a feature can be unitary even though the Constitution as a whole is federal.