Which of these is an archipelago nation?
indonesia
vietnam
laos
brunei

That would be Indonesia. It is considered as the world's largest archipelago with roughly 17,000 islands which span more than 5,000 km (an estimated 3,200 miles). There are 8 major islands or island groups which are: Sumatra, Java, Borneo, Celebes, and Irian Jaya (western half of Papua New Guinea). The smaller islands are divided into 2 main groups: the Mollucas to the northeast, and the lesser Sunda chain east of Bali. Bali would be the 8th since it is considered as a unique island.