The correct answer is D. Namrup in Assam.
The Namrup Fertiliser Plant is a public sector undertaking under the Ministry of Chemicals and Fertilizers, Government of India. It is located in Namrup, Assam, India. The plant was commissioned in 1976 and has a capacity of 1,200,000 tonnes per annum of urea. The plant is a major source of urea for the Indian market.
The other options are incorrect. Tuli is a town in Nagaland. Gangtok is the capital of Sikkim. Nangpo is a village in Meghalaya.