The correct answer is option 2, which is Part II of the Constitution. Part II of the Indian Constitution, titled "Citizenship," contains all the details related to citizenship. This part specifically deals with the laws and provisions regarding who is considered a citizen of India and the rights and responsibilities that come with Indian citizenship. It outlines the various ways through which a person can acquire or lose Indian citizenship, such as by birth, descent, registration, or naturalization. Part II also provides guidelines for determining the citizenship status of individuals in cases where there is a question or dispute. It is an essential part of the Constitution as it defines the legal status of Indian citizens and establishes the framework for their rights and duties.