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': 'Hebra nose is caused by: \nSelect and explain. \nA. Frisch bacillus, B. Staph aureus, C. Pseudomonas, D. C. diphtheriae', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is. 'a' i. e., Frisch bacillus", 'role': 'assistant'}]