Question: Which landlocked country in South Asia and one of the region's least populous nations has only four airports?
Sentence (from "Bhutan"): Located in the Eastern Himalayas, it is bordered by Tibet Autonomous Region in the north, India in the south, the Sikkim state of India and the Chumbi Valley of Tibet in the west, and Arunachal Pradesh state of India in the east.
Relevant evidence: No