The correct option is A Echinodermata
∙ The echinoderms are spiny-skinned organisms, which are exclusively free-living and marine. They are triploblastic and coelomate.
∙ They have a water-driven tube system for locomotion.
∙ The body consists of calcium carbonate structures that they use as skeletons.
E.g., Sea urchins, starfish.