The correct answer is A. Raigarh.
The Raigarh district is located in the eastern part of Chhattisgarh state, India. It is bordered by the Surguja district to the north, the Bilaspur district to the west, the Janjgir-Champa district to the south, and the Odisha state to the east. The district has a population of over 1.5 million people and its headquarters is the town of Raigarh.
The Raigarh district is known for its diamond reserves. The first diamond was found in the district in 1884 and since then, over 10 million carats of diamonds have been mined from the area. The diamonds from Raigarh are known for their high quality and are exported to all over the world.
The other options are incorrect. The Jagdalpur district is located in the southern part of Chhattisgarh state. The Raipur district is located in the central part of Chhattisgarh state. The Rajnandgaon district is located in the western part of Chhattisgarh state.