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': 'Scarlet fever is caused by? \nSelect and explain. \nA. Streptococci, B. Staphylococci, C. Klebsiella, D. Proteus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]