The Citizenship (Amendment) Act falls under Part II of the Constitution of India. Part II of the Constitution contains provisions related to citizenship. It specifically deals with the acquisition and termination of citizenship. The Citizenship (Amendment) Act, which was passed in 2019, amends the Citizenship Act of 1955 and provides for the granting of Indian citizenship to certain religious minority communities from Afghanistan, Bangladesh, and Pakistan who entered India before December 31, 2014.

Option 1, Part I of the Constitution of India, deals with provisions related to the Union and its territory. It contains articles pertaining to the establishment and organization of the Union, citizenship at the commencement of the Constitution, and how the territory of India is acquired, ceded, or divided.

Option 3, Part IV of the Constitution of India, deals with the Directive Principles of State Policy. These principles provide guidelines for the government`s functioning and aim to promote the welfare of the people.

Option 4, Part VI of the Constitution of India, deals with states and union territories. It contains articles related to the legislative and executive powers of the states and union territories.

Therefore, the correct answer is option 2.