Scorpion, Spider and Cockroaches are Arthropods and thus are Non-chordates. All non-chordates show presence of ventral nerve cord. In option (B), Centipede and prawn show jointed appendages as these are Arthropods but Sea urchin is an Echinoderm. In option (C), Cockroaches and Locust are Arthropods and hence body is divisible into head, thorax and abdomen while Taenia are flat worms and belong to Phylum Platyhelminthes and thus segmentation is absent. In option (D), Liver fluke shows bilateral symmetry. Sea anemone is Coelenterate and thus shows radial symmetry while sea cucumber belongs to Echinodermata which shows bilateral symmetry in larval stage and radial symmetry in adult stage.