The correct answer is: a) Sixth Schedule of the Constitution.
The Sixth Schedule of the Constitution of India provides for the administration of tribal areas in the states of Assam, Meghalaya, Tripura and Mizoram. The ADCs are established under this Schedule and are responsible for the administration of these areas.
The Panchayat Raj Act is a law that provides for the establishment of panchayats or village councils in India. The Right to Information Act is a law that gives citizens the right to access information held by the government. The Meghalaya Municipal Act is a law that provides for the establishment of municipalities in Meghalaya.
The ADCs are not established under any of these laws. They are established under the Sixth Schedule of the Constitution.