Porifera is the phylum of sponges. Sponges are filter feeders that live in marine and freshwater habitats.
Coral reefs are the characteristic feature of the phylum Cnidaria. Cnidaria is a phylum of aquatic invertebrates that includes corals, sea anemones, jellyfish, and hydras. Cnidarians are characterized by their radial symmetry, the presence of nematocysts (stinging cells), and a gastrovascular cavity (a single opening that serves as both a mouth and an anus). Coral reefs are built by colonial cnidarians called scleractinian corals. Scleractinian corals secrete a hard calcium carbonate skeleton that supports the reef structure. Coral reefs are found in warm, shallow waters around the world and are home to a wide variety of marine life.
Arthropoda is the phylum of insects, spiders, crustaceans, and other invertebrates. Arthropods are characterized by their segmented bodies and jointed appendages.
Platyhelminthes is the phylum of flatworms. Flatworms are parasitic or free-living invertebrates that have a flattened body plan.
Option B is correct.
Coral reefs are the characteristic feature of the phylum Cnidaria. Cnidaria is a phylum of aquatic invertebrates that includes corals, sea anemones, jellyfish, and hydras. Cnidarians are characterized by their radial symmetry, the presence of nematocysts (stinging cells), and a gastrovascular cavity (a single opening that serves as both a mouth and an anus). Coral reefs are built by colonial cnidarians called scleractinian corals. Scleractinian corals secrete a hard calcium carbonate skeleton that supports the reef structure. Coral reefs are found in warm, shallow waters around the world and are home to a wide variety of marine life.
The other options are not phyla that are characterized by coral reefs:
Porifera is the phylum of sponges. Sponges are filter feeders that live in marine and freshwater habitats.
Arthropoda is the phylum of insects, spiders, crustaceans, and other invertebrates. Arthropods are characterized by their segmented bodies and jointed appendages.
Platyhelminthes is the phylum of flatworms. Flatworms are parasitic or free-living invertebrates that have a flattened body plan.