The correct option is C a, c
The echinoderms belong to the phylum Echinodermata and subphylum Deuterostomia. Phylum Echinodermata belongs to kingdom Animalia, they are triploblastic animals. Examples of echinoderms include sea star, sea urchins etc. Echinoderms are marine animals, they are unisexual and their body have a tough spiny exoskeleton. Hence, the correct answer is the option C.