• Chiton belongs to the phylum Mollusca. It is a primitive elongated and is called sea cradles/sea mica. 
• It is covered by a dorsal shell and is made of many shell plates.
• They can be present in both warm as well as cold water.
• The common name of sea urchin is Sea biscuits.
• The binomial name provided to the specific species is called scientific name.

Hence, the correct option is A.