The correct answer is: B. Kaimur plateau.
The Kaimur plateau is a physiographic region that surrounds the North-Western part of Bihar. It is a hilly region that is part of the Chota Nagpur plateau. The Kaimur plateau is known for its rich mineral deposits, including coal, iron ore, and limestone. It is also a popular tourist destination, with several historical and religious sites located in the region.
The other options are incorrect because they are not physiographic regions that surround the North-Western part of Bihar.
- Someshwar hill range is a mountain range located in the South-Eastern part of Bihar.
- Nawada hilly region is a hilly region located in the Central part of Bihar.
- Rajgir hilly region is a hilly region located in the South-Western part of Bihar.