Who/Which of the following is the Custodian of the Constitution of India?

Correct answer: D, the Supreme Court of India. The Constitution does not use the word 'custodian' in any formal sense, but the Supreme Court is universally treated as its guardian because it interprets the document and decides whether any law or executive act conforms to it. Its powers flow from specific articles: Article 32 (writs for enforcement of Fundamental Rights), Article 131 (original jurisdiction in Centre-State and inter-State disputes), Article 137 (review of its own judgments), Article 141 (its law is binding on all courts) and Article 143 (advisory opinion).

• A (President): The President is the constitutional head and takes an oath to preserve, protect and defend the Constitution under Article 60, but this is an oath of office, not a power to adjudicate constitutionality. Executive power is exercised on the advice of the Council of Ministers under Article 74.
• B (Prime Minister): The PM heads the government and the Council of Ministers. He has no judicial or custodial role over the Constitution.
• C (Lok Sabha Secretariat): It is an administrative body that supports the Lok Sabha's functioning. It has no authority over constitutional interpretation.

Core concept: Judicial review and the basic structure doctrine, settled in Kesavananda Bharati (1973). This links directly to the Mains theme of separation of powers and the judiciary's role in checks and balances.

Trap: Students pick A because the President's oath under Article 60 says 'preserve, protect and defend'. The oath is a duty of office, while the power to interpret the Constitution rests with the Supreme Court.