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

The Supreme Court of India is the correct answer because it acts as the final interpreter and guardian of the Constitution, utilizing the power of judicial review to strike down any law or executive action that violates the constitutional framework. While the President is often a tempting choice because their oath (Article 60) includes "preserving, protecting, and defending" the Constitution, this is a formal executive duty rather than the judicial authority to interpret and enforce constitutional provisions. The core concept being tested is the role of the Judiciary as the ultimate protector of the Constitution and fundamental rights.