Explanation:

This question pertains to the recognition and status of tribal languages in West Bengal. \nOption A, 'Sadri', is incorrect. Sadri is an Indo-Aryan language spoken by the Sadan people in the Chota Nagpur Plateau region, including parts of Jharkhand, Bihar, Chhattisgarh, and Odisha. While it has a significant number of speakers, it is not the specific language that fits the criteria of being given official status in West Bengal and simultaneously being regarded as endangered by UNESCO. \nOption B, 'Kurmali', is the correct answer. Kurmali (also known as Kudmali) is an Indo-Aryan language spoken by the Kurmi Mahato community, primarily in parts of West Bengal, Jharkhand, and Odisha. The West Bengal Official Language Act, 2012, recognized Kurmali as an official language in specific areas of West Bengal. UNESCO has indeed identified Kurmali as an endangered language, highlighting the need for its preservation and promotion. \nOption C, 'Kurukh', is incorrect. Kurukh (also known as Oraon) is a Dravidian language spoken by the Oraon and Kisan tribal communities in parts of Jharkhand, Chhattisgarh, Odisha, West Bengal, and Assam. While it is a significant tribal language, it does not fit the specific criteria of official status in West Bengal while being listed as endangered by UNESCO in the context of this question. \nOption D, 'Santali', is incorrect. Santali is the most widely spoken language of the Munda subfamily of Austroasiatic languages, spoken by the Santal people. It is recognized in the Eighth Schedule of the Constitution of India, meaning it has official status at the national level, and is widely spoken in West Bengal, Jharkhand, Odisha, and Bihar. Due to its constitutional recognition and large number of speakers, it is not typically classified as endangered by UNESCO in the same context as Kurmali.