Amoebic dysentery is caused by which of the following? fungi viruses protists bacteria

Amoebic dysentery is caused by a protist, or protozoa. A protist is a unicellular organism usually found  living in water or as a parasite in a host such as man. 
Amoebic dysentery is caused by one of two very similar looking protists that invade and live in the gut of man. These are Entamoeba coli and Entamoeba histolytica and they gain access in the gut of man through ingestion in form of cysts in contaminated water and food.This is the primary mode of infection.

Entamoeba coli is known to be a harmless intestinal protozoa and does not cause any significant ill effects. Entamoeba histolytica on the other hand is the culprit behind amoebic dysentery invading and perforating the gut lining causing bleeding, ulceration and intense irritation leading to dysentery. It feeds on red blood cells. 

Entamoeba histolytica is effectively eliminated from the gut by medication.