The correct answer is D. Sadari.
Gondi is a Dravidian language spoken by the Gond people of central India. It is the official language of the Bastar district of Chhattisgarh.
Halbi is a language spoken by the Halbi people of central India. It is a mix of Gondi and Hindi.
Bhatri is a language spoken by the Bhatra people of central India. It is a mix of Gondi and Telugu.
Sadari is a language spoken by the Sadari people of central India. It is a mix of Gondi and Marathi.
Gondi, Halbi, and Bhatri are all languages of the Bastar region. Sadari is not a language of the Bastar region.