The Maldives is composed of hundreds of coral atolls, and the highest point is just 5 meters above sea level, with the average elevation just 1.5 meters.
Actually, there are 26 physical atolls. "Physical" because atoll is a loan word from Dhivehi, where atolhu means "province." (Maldivian political atolls often correspond with physical atolls, but some physical atolls are split and others are combined.) The atolls in the north are oldest and are degraded, so that there is virtually no ring reef left, whereas in the south they are younger and it's much easier to see the ancient shoreline of the now-submerged volcanic islands. Enjoyed the quiz.
It's asking about which countries have their land spread out most over different islands. To measure this the following method is used. Countries that are not spread out will have most of their land on one or two landmasses (the UK, for example, has almost all of its land on Great Britain or Ireland). For this reason this quiz is using the smallest percentage of the land lying on an island that is the largest or second-largest island in the country.
I was really surprized of Micronesia, which I assumed was like Marshall Island or Tuvalu, but then I checked and there is two "really big" islands, Pohnpei and Weno, and then just atolls.