The correct answer is: c) Preserve and protect religious institutions and traditions.
Article 371F of the Indian Constitution provides for special provisions with respect to the state of Nagaland. One of these provisions is the establishment of an Ecclesiastical Department to preserve and protect religious institutions and traditions of the Naga people. The Department is responsible for matters such as the registration of churches, the appointment of priests, and the management of religious endowments.
Option a) is incorrect because the Ecclesiastical Department is not responsible for promoting religious harmony. This is a responsibility of the state government.
Option b) is incorrect because the Ecclesiastical Department is not responsible for enforcing a state religion. India is a secular state and there is no state religion.
Option d) is incorrect because the Ecclesiastical Department is not responsible for collecting taxes from religious organizations. This is a responsibility of the central government.