Which characteristic is unique to cephalopods? They have a radula. They can live in water or on land. They have a closed circulatory system. They can produce pearls.

Option C, They have a closed circulatory system

Explanation:

Cephalopods belong to phylum Mollusca and are unique in sense that they have a closed circulatory system. This closed circulatory system consists of three unusual hearts with arteries, veins, and capillaries. Excepts Cephalopods, all majority of mollusks have open circulatory system. In open systems, heart pumps blood through blood vessels into the gills and then into body cavities (hemocoels)

Hence, option C is correct

oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.