Best known "Apicomplex" is the:

Explanation

Apicomplexan, also called sporozoan, are protozoan of the (typically) spore-producing phylum Apicomplexa. All apicomplexans are parasitic and lack contractile vacuoles and locomotor processes.Malaria is caused by a single-celled parasite of the genus Plasmodium. The malarial parasite, plasmodium, is the best-known apicomplexa. All Plasmodium species share a similar life cycle. It has two parts-in the first, the parasite infects a person (or a vertebrate host), and in the second, it is transmitted from the malaria patient (or infected vertebrate host) to another host by an insect vector.