Explanations:Understanding the geographical layout of northeastern India is crucial for identifying which state is surrounded by Bangladesh on three sides. The northeastern region of India comprises seven states, commonly referred to as the "Seven Sister States," along with the state of Sikkim. These states are Assam, Arunachal Pradesh, Manipur, Meghalaya, Mizoram, Nagaland, Tripura, and Sikkim.
Among these states, Tripura stands out due to its unique geographical position. Tripura is located in the eastern part of the northeastern region and is almost entirely surrounded by Bangladesh. Specifically, it shares borders with Bangladesh on its north, west, and south, which means it is encircled by Bangladesh on three sides. This geographical feature makes Tripura distinct from other northeastern states.
It is important to note that while other northeastern states like Meghalaya and Mizoram also share borders with Bangladesh, they do not have the same encirclement as Tripura. Meghalaya shares a border with Bangladesh but is also bordered by Assam and Nagaland. Mizoram shares a border with Bangladesh but is also bordered by Manipur and Assam. West Bengal, while sharing a long border with Bangladesh, is not encircled by it on three sides.
Therefore, the correct answer is Tripura, as it is the only state in northeastern India that is almost entirely surrounded by Bangladesh on three sides. This geographical feature is significant for understanding the political and economic relationships between India and Bangladesh, as well as the unique challenges and opportunities faced by Tripura due to its border situation.