Vietnam shares land borders with China, Laos, and which other country?

The correct answer is Cambodia. Vietnam has exactly three land-border neighbours: China to the north, Laos to the west, and Cambodia to the southwest, as confirmed by the CIA World Factbook's boundary data. Vietnam's territory runs in a long S-shape down the eastern edge of the Indochinese peninsula, and its southwestern stretch, including the Mekong Delta region, borders Cambodia along a line that has been the subject of historical territorial disputes and demarcation agreements between the two countries over past decades. This border also matters economically because the Mekong River crosses from Cambodia into Vietnam before reaching the sea, linking the two nations' geography and water resources. Thailand (option B) is incorrect because although it lies in the same mainland Southeast Asian region, it does not share a physical boundary with Vietnam; Laos and Cambodia lie between them. Myanmar (option C) is also incorrect for the same reason; it borders Thailand, China and India but is geographically separated from Vietnam by several countries. Malaysia (option D) is incorrect because it lies further south, primarily on the Malay Peninsula and the island of Borneo, with no shared frontier with mainland Vietnam at all. A frequent mistake among students is to assume that any ASEAN member located broadly in Southeast Asia must share a border with Vietnam, when in fact only Cambodia, Laos and China do. Revision takeaway: memorise Vietnam's three neighbours together as China (north), Laos (west) and Cambodia (southwest), and note that Thailand, Myanmar and Malaysia, though regionally close, are not among them.