The correct answer is option 2, which is Part II of the Constitution. This part of the Constitution of India includes Articles 5 to 11, which specifically mention the details of citizenship in India.
Option 1, Part I of the Constitution, pertains to the Union and its territories. It does not deal with the topic of citizenship.
Option 3, Part III of the Constitution, contains the fundamental rights of citizens in India. While it indirectly relates to citizenship by discussing various rights and freedoms, it does not explicitly mention the details of citizenship.
Option 4, Part IV of the Constitution, covers the Directive Principles of State Policy. Again, while this part indirectly relates to citizens, it does not provide specific details about citizenship.
Overall, it is clear that Part II of the Constitution is the correct part that contains the details of citizenship in India.