Which of the following is an atoll formed from coral reefs?

The Maldives is indeed an example of an atoll formed from coral reefs. Atolls are ring-shaped coral reefs that encircle a lagoon partially or completely. The Maldives is an archipelago consisting of 26 atolls, characterized by numerous small islands that have formed around the fringes of submerged volcanic islands. Over time, the growth of coral reefs around these islands has led to their transformation into atolls as the volcanic island erodes and sinks.

In contrast, Bora Bora is a volcanic island in French Polynesia with a lagoon, but it does not primarily consist of coral atolls. The Great Barrier Reef, while a massive coral reef system, is not an atoll but rather a series of reefs and islands extending along the Australian coast. The Galapagos Islands are also volcanic islands and do not form atolls. Thus, the Maldives stands out as a distinct example of an atoll formed specifically from coral reefs.