This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: AIIMS 2017, Subject name: Microbiology
Cyst of parasite seen in stool microscopy. What is the organism? 
Select and explain. 
A. Entamoeba dyspar, B. Balantidium coli, C. Giardia lambia, D. Taenia solium
C: Giardia lambia
Answer: C: Giardia lambia 
Explanation: The given cyst have axostyle and 4 nuclei are present - features of Giardia lamblia. Trophohozoites of Giardia lamblia have 4 pairs of flagella and have falling leaf like motility. Balantidium coli- cyst are binucleated Entamoeba dyspar- quadrinucleated cyst no axostyle Taenia solium-no cyst eggs are seen in faeces