How Do Atolls Form

question 18

Multiple Choice

How do atolls form?

• A) A fringing reef around a volcanic island grows upward as the island sinks.
• B) A caldera on a volcanic island fills with water.
• C) The central portion of a reef sinks below sea level, leaving a ring around the outer edge.
• D) Organisms on the outer edge of a reef grow more quickly than organisms in the center.

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