The correct answer is A. 1850.
The first printing press in Bihar was established in 1850 by the Serampore Mission. The press was set up in Patna and printed a variety of materials, including religious texts, educational books, and newspapers. The press played an important role in the development of education and literacy in Bihar.
Option B is incorrect because the Serampore Mission established the first printing press in Bihar in 1850, not in 1899.
Option C is incorrect because India gained independence from British rule in 1947, and the first printing press in Bihar was established in 1850.
Option D is incorrect because the first printing press in Bihar was established in 1850, not in 1971.