All three pairs are correctly matched based on historical and administrative facts about the states in question.

I. Arunachal Pradesh has its capital, Itanagar, which is named after the Ita Fort, and the state is home to two significant national parks: Namdapha and Pakke, highlighting its rich biodiversity.

II. Nagaland was established as a state through the 13th Amendment to the Indian Constitution in 1962, recognizing the unique cultural aspirations of the Naga people, thus reflecting the constitutional provisions for the formation of states based on specific criteria.

III. Tripura, originally classified as a Part 'C' state, was restructured into a centrally administered territory in 1956 before being granted statehood in 1972, illustrating the evolution of administrative divisions in India post-Independence.

These descriptions underscore the importance of India's federal structure and the historical context surrounding the formation and evolution of its states, which are essential concepts in the UPSC syllabus regarding Indian polity and governance.