Option 1 -> Tripura is located in Northeast India but shares its borders with Bangladesh, not Bhutan.
Option 2 -> Manipur is a landlocked state in Northeast India that does not share a border with Bhutan; it borders Myanmar.
Option 3 -> Mizoram shares international borders with Bangladesh and Myanmar, but not with Bhutan.
Option 4 -> Sikkim is located in the Eastern Himalayas and shares its northern border with Bhutan.
Hence, Option 4: Sikkim -> Four Indian states share borders with Bhutan: Sikkim, West Bengal, Assam, and Arunachal Pradesh. Among the given options, only Sikkim borders Bhutan -> correct