Answer: The correct answer is -
b. echinoderms.
Arthropoda is a phylum of invertebrates that includes organisms with jointed appendages and it is the largest phylum.
Echinodermata is a different phylum of invertebrates that includes exclusively marine organisms with three germ layers and true coelom.
Example of Echinoderms- Starfish.
Thus, option b) Echinoderms is the right answer.
