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': 'Patient complaining of retrosternal chest pain for more than half an hour is most likely to be: \nSelect and explain. \nA. Angina, B. MI, C. CHF, D. Congenital heart problem', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]