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: ENT
[{'content': 'Otitis externa Haemorragica is caused by: \nSelect and explain. \nA. Influenza, B. Proteus, C. Staph, D. Streptococcus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Otitis externa haemorrhagica is most commonly caused by influenza virus and is characterised by formation of haemorrhagic bullae on the tympanic membrane.', 'role': 'assistant'}]