The correct answer is D, inhalation of spores in dust.  Entamoeba histolytica, the agent of amebic colitis and liver abscess, does not produce spores at any stage in its life cycle.  The disease is prevented and controlled by improved sanitation and treatment of water sources.

Click here to open a new window with a schematic showing the life cycle of Entamoeba histolytica.  Close the new window to return to this page.