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: Medicine
[{'content': 'The causative organism of rheumatic heart disease associated with rheumatic fever are: \nSelect and explain. \nA. Beta hemolytic streptococci, B. Beta hemolytic staphylococci, C. Alpha hemolytic streptococci, D. Gamma hemolytic streptococci', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]