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
[{'content': 'Cyst stage is absent in \nSelect and explain. \nA. Dientamoeba fragilis, B. Entamoeba coli, C. Entamoeba histolytica, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Dientamoeba fragilis is a parasite that lives in the large intestine of people.\xa0\nThis protozoan parasite produces trophozoites; cysts have not been identified.\xa0\nThe intestinal infection may be either asymptomatic or symptomatic.\xa0\nMany infected people do not have any symptoms.\xa0\nThe most common symptoms are diarrhea and abdominal pain.\xa0\nSymptoms also can include loss of appetite, weight loss, nausea, and fatigue.\xa0\nThe infection does not spread from the intestine to other parts of the body.\nEntamoeba coli and Entamoeba histolytica both have cyst stage.\u200b\n\nRef :https://www.cdc.gov/parasites/dientamoeba/index.html', 'role': 'assistant'}]