The correct answer is C. Jamalpur.
Jamalpur is a city in the Indian state of Bihar. It is the headquarters of Jamalpur district and is located on the banks of the Ganges River. The city is known for its railway workshop and rail wheel plant. The railway workshop was established in 1862 and is one of the oldest in India. The rail wheel plant was established in 1984 and is the largest in India.
The other options are incorrect. Bela is a town in the Indian state of Bihar. It is located in the Saran district. Madhepura is a city in the Indian state of Bihar. It is the headquarters of Madhepura district. Mokama is a town in the Indian state of Bihar. It is located on the banks of the Ganges River.