The correct answer is option 1: Arunachal Pradesh. The state of Arunachal Pradesh was formed after the amendment of articles 239A and 240.

Article 239A deals with the administration and control of the Union Territory of Delhi. It empowers the President to make regulations for the peace, progress, and good governance of Delhi. This article was inserted into the Constitution by the 69th Amendment Act, 1991.

Article 240 deals with the administration of Union Territories. It empowers the President to make regulations for the peace, progress, and good governance of any Union Territory directly under the President`s rule. This article was amended to include provisions for forming new states and altering the boundaries of existing states.

Therefore, it was through the amendment of articles 239A and 240 that the state of Arunachal Pradesh was formed.