The correct answer is: B. 1, 2 and 3.
Bihar Sharif was an important center of trade, learning, and administration in the medieval period. It was located on the banks of the Son River, which made it a natural hub for trade between the Ganges Valley and the Deccan Plateau. The town was also home to a number of important educational institutions, including the madrasa of Firuz Shah Tughluq. Bihar Sharif was also the capital of the Sultanate of Jaunpur from 1394 to 1479.
Option A is incorrect because it does not include the option of Bihar Sharif being a center of administration. Option C is incorrect because it does not include the option of Bihar Sharif being a center of trade. Option D is incorrect because it does not include the option of Bihar Sharif being a center of learning.