In which of the following States is Birhor tribe found?

The correct option is Bihar.

The Birhor tribe is a nomadic, particularly vulnerable tribal group (PVTG) traditionally found primarily in the eastern Indian states of Jharkhand, Bihar, Odisha, West Bengal, and Chhattisgarh.
Their language, Birhor, belongs to the Munda group of the Austroasiatic language family.

Analyzing the given options:
- Bihar: Historically and currently, the Birhor people inhabit regions of the Chota Nagpur Plateau, which extends across Jharkhand and parts of Bihar. Thus, among the options provided, Bihar is the correct state where the Birhor tribe is found.
- Assam: Primarily home to tribes like Bodo, Mishing, and Karbi.
- Rajasthan: Known for tribes like Bhils, Minas, and Sahariyas.
- Nagaland: Inhabited by Naga tribes such as Ao, Angami, and Lotha.