Question

1. what forms atolls?

a. underwater volcanoes
b. tectonic movement
c. coral reefs

Explanation:

Define atolls and their characteristics

Atolls are ring-shaped coral reefs, islands, or series of islets.
They surround a central body of water called a lagoon.

Identify the primary building material

Using the Oceania Islands knowledge point, we analyze island types.
Atolls are built by organic processes rather than geological uplift.
They are formed primarily by colonies of tiny marine organisms.

Analyze the formation process

Coral reefs grow around a subsiding volcanic island.
As the island sinks, the coral continues growing upward.
Eventually, only the ring of coral remains visible.
Therefore, coral reefs are the direct physical structures forming atolls.

Answer:

• A. underwater volcanoes
• B. tectonic movement
• C. coral reefs (Correct answer)