Select the option that correctly matches a characteristic feature with the group of three animals.

Snail, squid and chiton are molluscs. They have a file-like rasping organ called radula in the buccal cavity. Calcareous ossicles are absent in sea hare (Aplysia, a mollusc). Scorpion respires by book lungs. Squid respires by gills. Stomochord is present in hemichordates; not in Limulus (arthropod).