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

The correct answer is The Supreme Court of India.

Explanation:
The Supreme Court of India is regarded as the "Custodian of the Constitution of India". This role is established through several key features and powers granted to the judiciary by the Constitution itself:
1. Judicial Review: Under Article 13 and other provisions of the Constitution, the Supreme Court has the power of judicial review. This allows the Court to examine the constitutionality of legislative enactments and executive orders passed by the government. If any law or order is found to violate the provisions of the Constitution, the Supreme Court has the authority to declare it null, void, and unconstitutional.
2. Guardian of Fundamental Rights: Article 32 (Right to Constitutional Remedies) empowers citizens to directly approach the Supreme Court for the enforcement of their Fundamental Rights. The Court can issue writs such as Habeas Corpus, Mandamus, Prohibition, Quo Warranto, and Certiorari to protect citizens' rights from infringement.
3. Final Interpreter: The Supreme Court is the ultimate authority to interpret the meaning and intent of the clauses written within the Constitution of India. Its decisions are final and binding on all courts and authorities within the territory of India.

Thus, by acting as the final interpreter, safeguarding fundamental rights, and keeping check on executive and legislative actions, the Supreme Court of India serves as the Custodian of the Constitution.