The correct answer is C, Blastocystis hominis.  B. hominis appear as spherical to oval cyst-like structures.  They can vary widely in size (5 to 30 µm; usual range 8 to 10 µm), and typically consist of a central body, or "vacuole" surrounded by a thin rim of cytoplasm containing up to six nuclei.

Click here to open a new window with more information about B. hominis.  Close the new window to return to this page.