The correct answer is C. Santhal Pargana region (Western part).
Old alluvial soil is found in the western part of the Santhal Pargana region. It is a type of soil that is formed from the deposition of sediments by rivers. It is a fertile soil that is good for agriculture.
The Latehar region is located in the eastern part of the Santhal Pargana region. It is a hilly region with a different type of soil.
The Hazaribagh region is located in the central part of the Santhal Pargana region. It is a hilly region with a different type of soil.
Sahibganj is located in the eastern part of the Santhal Pargana region. It is a hilly region with a different type of soil.
Old alluvial soil is a type of soil that is formed from the deposition of sediments by rivers. It is a fertile soil that is good for agriculture. It is found in the western part of the Santhal Pargana region.