This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General surgery, Subject name: Surgery
[{'content': 'Chronic Burrowing ulcer is caused by \nSelect and explain. \nA. Microaerophilic streptococci, B. Peptostreptococcus, C. Streptococcus viridans, D. Streptococcus pyogenes', 'role': 'user'}, {'content': "Answer: A \nExplanation: Microaerophilic streptococci (Burrowing ulcer / Maleny's ulcer is caused by synergistic infection of microaerophilic non hemolytic streptococci and aerobic hemolytic streptococci)", 'role': 'assistant'}]