The correct answer is Myanmar.
The Yu River is a river in India and Myanmar. It is a tributary of the Chindwin River. The river rises in the Manipur Hills in India and flows south into Myanmar. It forms part of the border between Manipur and Myanmar. The river then flows east and joins the Chindwin River near Kalewa.
The Yu River is a major source of water for irrigation and drinking water in Manipur and Myanmar. The river is also a popular destination for fishing and boating.
The other options are incorrect because they are not borders of Manipur.
- Myanmar is a country in Southeast Asia. It is bordered by China, India, Bangladesh, Laos, and Thailand.
- Nagaland is a state in northeastern India. It is bordered by Assam, Manipur, and Myanmar.
- Mizoram is a state in northeastern India. It is bordered by Assam, Manipur, Tripura, and Bangladesh.
- Assam is a state in northeastern India. It is bordered by Bhutan, China, Nagaland, Manipur, Mizoram, Tripura, Meghalaya, and West Bengal.