The confluence of the rivers Tlawng and Tut is significant because it forms the:

The correct answer is: a) Kolodyne (Chhimtuipui).

The confluence of the rivers Tlawng and Tut is significant because it forms the Kolodyne (Chhimtuipui) River. The Kolodyne River is a major river in Mizoram, India. It is the longest river in the state, with a length of about 200 kilometers. The river originates in the hills of the Mizo Hills and flows eastwards to join the Barak River in Tripura. The Kolodyne River is a major source of water for irrigation and drinking water in Mizoram. It is also a popular destination for fishing and boating.

The other options are incorrect because:

• Option b) Mat River is a tributary of the Kolodyne River.
• Option c) Khawthlangtuipui (Karnaphuli) is a river in Bangladesh.
• Option d) Tuivai is a river in Manipur, India.