A. Plasmodium falciparum.
B. Plasmodium vivax.
C. Entamoeba coli.
D. Balanitidium coli.
The trophozoite shown in Photograph above represents Balanitidium coli.
Balantidium coli is a parasitic species of ciliate alveolates that causes the disease balantidiasis. It is the only member of the ciliate phylum known to be pathogenic to humans.