Open circulatory system is present in: (I) Arthropods. (II) Annelids. (III) Chordates. (IV) Molluscs

Explanation

The species in the phylum arthropoda have an open circulatory system. Open circulatory systems work by pumping the blood into a hemocoel. Molluscs have open circulatory systems like a snail, chiton, slug, etc, except for cephalopods which have closed circulatory systems. In Annelids the circulatory system is usually closed, i.e., confined within well-developed blood vessels. But in some polychaetes and leeches, the circulatory system is partly open, with blood and coelomic fluid mixing directly in the sinuses of the body cavity. Chordates also have a closed circulatory system, which can be either single or double looped. and most, but not all, chordates have a heart. Thus, the correct answer is option C.