Based on the search results, all three pairs are correctly matched: I. Arunachal Pradesh: Itanagar, the capital of Arunachal Pradesh, is named after the Ita Fort, which means 'fort of bricks.' The state has two national parks: Namdapha National Park and Mouling National Park. II. Nagaland: The state was formed by the State of Nagaland Act, 1962, which was enacted following the Thirteenth Amendment to the Indian Constitution. III. Tripura: Initially a Part 'C' state, Tripura became a Union Territory in 1956 and later attained full statehood on January 21, 1972, under the North-Eastern Areas (Reorganisation) Act, 1971.