The correct answer is: B. Gaya
Tal soil is a type of alluvial soil that is found in the Ganges Plain. It is a dark, loamy soil that is rich in organic matter. Tal soil is well-drained and has a high water-holding capacity. It is suitable for growing a variety of crops, including rice, wheat, and sugarcane.
The tal soil belt is spread from Buxar in the west to Bhagalpur in the east. It is also found in the districts of Gaya, Patna, and Nalanda. The tal soil belt is a major agricultural region in India.
Option A: Champaran is a district in the state of Bihar. It is located in the northern part of the state. The soil in Champaran is mostly alluvial soil.
Option B: Gaya is a district in the state of Bihar. It is located in the central part of the state. The soil in Gaya is mostly alluvial soil.
Option C: Bhagalpur is a district in the state of Bihar. It is located in the eastern part of the state. The soil in Bhagalpur is mostly alluvial soil.
Option D: Banka is a district in the state of Bihar. It is located in the southern part of the state. The soil in Banka is mostly alluvial soil.