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': "The 'String of pearl' colonies on nutrient agar is produced by: September 2004 \nSelect and explain. \nA. Klebsiella, B. Proteus, C. Bacillus, D. Salmonella", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C i.e. Bacillus', 'role': 'assistant'}]