The correct answer is A. 1860.
The first railway line in Bihar was opened in 1860 between Patna and Arrah. The line was extended to Gaya in 1862 and to Kolkata in 1864. The development of railways in Bihar was a major factor in the state’s economic development. The railways helped to improve transportation and communication, and they also helped to open up new areas for agriculture and industry.
Option B is incorrect because the development of railways in Bihar was not started in 1890. The first railway line in Bihar was opened in 1860.
Option C is incorrect because the development of railways in Bihar was not started in 1920. The first railway line in Bihar was opened in 1860.
Option D is incorrect because the development of railways in Bihar was not started in 1950. The first railway line in Bihar was opened in 1860.