Explanation
Why Correct: Part II of the Constitution, comprising Articles 5 to 11, exclusively governs citizenship, detailing provisions for acquisition at commencement, citizenship by birth, descent, registration, naturalization, and termination.
Distractor Analysis: Part I defines the Union and its territory, including state formation and reorganization. Part III enshrines Fundamental Rights guaranteed to citizens and in some cases to all persons. Part IV contains Directive Principles of State Policy, which are non-justiciable guidelines for governance.
Takeaway:</strong: The Citizenship Act of 1955, enacted under Article 11, provides the statutory framework for citizenship matters, while Part II sets the constitutional foundation.