The correct answer is: C. Kosali
Kosali is an Indo-Aryan language spoken in the Indian states of Chhattisgarh, Odisha, and Jharkhand. It is the native language of the Chhattisgarhi people. Kosali is a member of the Eastern Hindi group of languages, and is closely related to Awadhi, Bhojpuri, and Magahi.
Halbi is a language spoken by the Halbi people of Chhattisgarh. It is a member of the Dravidian language family, and is closely related to Gondi.
Awadhi is a language spoken in the Indian states of Uttar Pradesh, Bihar, and Jharkhand. It is a member of the Eastern Hindi group of languages, and is closely related to Bhojpuri, Magahi, and Kosali.
Mahakantriya is a language spoken in the Indian state of Chhattisgarh. It is a member of the Munda language family, and is closely related to Kurukh and Oraon.
None of these is the correct answer.