For coral reefs to form in tropical waters, it is necessary for the coral animals to live in symbiosis with:

A) bacteria.
B) parrot fish.
C) zooxanthellae.
D) sea urchins.
E) kelp.

Coral Reefs

Marine ecosystems characterized by reef-building corals; known for their biodiversity, they are often referred to as the "rainforests of the sea."

Tropical Waters

Warm ocean water found near the equator, characterized by high temperatures and supporting diverse marine life.

Zooxanthellae

Photosynthetic algae found in close symbiotic relationships with marine invertebrates such as corals and sea anemones.