The Sixth Schedule of the Indian Constitution provides for the administration of tribal areas in Assam, Meghalaya, Tripura, and Mizoram. Parts of Arunachal Pradesh are also governed under the Sixth Schedule. This implies:

The correct answer is: a) Decentralized governance through Autonomous District Councils.

The Sixth Schedule of the Indian Constitution provides for the administration of tribal areas in Assam, Meghalaya, Tripura, and Mizoram. Parts of Arunachal Pradesh are also governed under the Sixth Schedule. This implies decentralized governance through Autonomous District Councils.

Autonomous District Councils are elected bodies that have the power to make laws on matters affecting the tribal people in their areas. They also have the power to collect taxes and to administer justice. The Sixth Schedule provides for a system of checks and balances between the Autonomous District Councils and the central government. This ensures that the tribal people have a say in their own affairs, while also protecting their rights.

The other options are incorrect because:

• Option b) Direct rule by the central government is not the case under the Sixth Schedule. The Autonomous District Councils have a significant degree of autonomy.
• Option c) Complete integration with mainstream administrative systems is also not the case. The Sixth Schedule provides for a system of decentralized governance that is tailored to the needs of the tribal people.
• Option d) Primacy of tribal customary laws is not the only consideration under the Sixth Schedule. The Autonomous District Councils also have the power to make laws on matters affecting the tribal people, and to collect taxes and to administer justice.