The correct answer is: a) Alluvial soil.
Alluvial soil is the most common type of soil found in Bihar. It is a type of soil that is formed by the deposition of sediments from rivers and streams. Alluvial soil is typically rich in nutrients and is well-drained, making it ideal for agriculture.
Red soil is a type of soil that is found in tropical and subtropical regions. It is typically reddish-brown in color and is rich in iron oxide. Red soil is not as fertile as alluvial soil, but it is still suitable for agriculture.
Black soil is a type of soil that is found in semi-arid and sub-humid regions. It is typically black or dark brown in color and is rich in organic matter. Black soil is very fertile and is well-suited for growing crops such as rice, wheat, and soybeans.
Laterite soil is a type of soil that is found in tropical and subtropical regions. It is typically reddish-brown or yellow in color and is rich in iron and aluminum oxides. Laterite soil is not as fertile as other types of soil and is prone to erosion.
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