The correct option is B Ctenophora, Echinodermata
Animals of the phyla Echinodermata, Cephalochordata and Ctenophora are exclusively marine.
Members of phylum Cnidaria are aquatic. They can live both in freshwater and marine environments.
Members of phylum Mollusca can be both aquatic and terrestrial.
Members of phylum Arthropoda are found in a variety of aquatic and terrestrial habitats.