Statement (a) is correct; Article 371A provides special provisions for the State of Nagaland. Statement (b) is correct; Article 371A(1)(a) explicitly states that no Act of Parliament in respect of the religious or social practices of the Nagas, Naga customary law and procedure, administration of civil and criminal justice involving decisions according to Naga customary law, and ownership and transfer of land and its resources shall apply to the State of Nagaland unless the Legislative Assembly of Nagaland by a resolution so decides. Statement (c) is incorrect; while Tuensang district is covered under special administrative provisions in Article 371A(1)(b) due to its unique historical situation, it is generally considered a less developed area compared to other parts of Nagaland, not the most developed.