The correct answer is option 4, Tripura. Tripura is a state in northeastern India, bordered by Bangladesh on three sides. It does not share an international border with any other country apart from Bangladesh.

Let`s examine the other options to understand why they are not the correct answer.

Option 1, Arunachal Pradesh: Arunachal Pradesh is a state situated in the far northeast of India. It shares international borders with both China and Bhutan.

Option 2, Assam: Assam is a state in northeastern India. It shares an international border with Bhutan to the north and Bangladesh to the south.

Option 3, Mizoram: Mizoram is also a state in northeastern India. It shares international borders with both Bangladesh and Myanmar.

Therefore, the only option that does not share an international border with two or more countries is option 4, Tripura.