This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Non-pathogenic amoebae is/are -a) E. histolyticab) E.coli.c) Acanthamoebad) E.Hartmannie) Balamuthia 
Select and explain. 
A. c, B. d, C. ab, D. bd
D: bd
Answer: D: bd 
Explanation: Non-pathogenic amebae are E.hartmanni, E.coli, E.polecki, Endolimax nana, Iodamoeba botschlii, and Dientamoeba fragilis.