The Tribal Welfare Department of Andhra Pradesh works to preserve and promote tribal languages through:

The correct answer is: d) All of the above

The Tribal Welfare Department of Andhra Pradesh works to preserve and promote tribal languages through a variety of initiatives, including:

• Documentation and research: The department works to document and research tribal languages, including their grammar, vocabulary, and history. This information is used to create educational materials and resources, as well as to develop programs that promote the use of tribal languages.
• Education in tribal languages: The department provides education in tribal languages through a variety of programs, including early childhood education, primary education, and adult literacy. These programs help to ensure that tribal children and adults have the opportunity to learn and use their native languages.
• Cultural programs and festivals: The department organizes cultural programs and festivals that celebrate tribal languages and cultures. These events provide opportunities for tribal people to share their languages and cultures with others, and to promote understanding and appreciation of tribal languages.

The Tribal Welfare Department of Andhra Pradesh is committed to preserving and promoting tribal languages, and its work is essential to the survival of these languages.