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': 'A patient presents to the emergency department with history of persistent fever & cough. Radiological features are suggestive of pneumonia. Sputum examination cultures reveal aerobic branching Gram positive filaments that are partially acid fast.Which of the following is the most likely etiological agent - \nSelect and explain. \nA. Actinomyces israeli, B. Nocardia asteriodes, C. Aspergillus fumigatus, D. Staphylococcus aureus', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]