help summer hw question?

lets say You have just arrived at Bora Bora, a very pretty atoll in the TahitianIsland chain. Given the knowledge of how atolls are formed, why doesBora Bora have a central island in the middle of the lagoon whereas most atolls do not?

a. Volcanic activity is pushing the central land mass upwards

b. The fringing reef has not had a chance to erode the central land mass

c. The central land mass has not completely subsided below the ocean’s

surface yet

d. The island was formed by sedimentation from the nearby island of Tahiti.