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': 'Most common agent causing tuberculosis in AIDS patient in tropical countries is - \nSelect and explain. \nA. Mycobacterium tuberculosis, B. Mycobacterium intracellulare, C. Mycobacterium parvum, D. Mycobacterium atypical', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]