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': 'Protozoa associated with megaesophagus \nSelect and explain. \nA. Trypanosome, B. Amoeba, C. Giardia, D. Gnathostoma', 'role': 'user'}, {'content': "Answer: A \nExplanation: Megaesophagus and megacolon occur as complications of chronic Chagas disease.\nT. cruzi causes Chagas' disease \nChaga's disease\n\n1.\xa0 Acute form\n\nOccurs in infants and children.\nPresents with fever, unilateral face swelling, lymphadenopathy, splenomegaly and chagoma (Localized swelling of the skin).\n\n2.\xa0 Chronic form\n\nOccurs in adolescent and adults\nPresents with cardiac arrhythmias and neurological manifestations.\nComplications → megacolon, megaesophagus, cardiomyopathy.\n\nRomana's sign\nWhen entry of the parasite is through the conjunctiva, an edematous swelling of eyelids of one eye develops.", 'role': 'assistant'}]