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: Pathology
[{'content': "Mc Callum's patch is diagnostic of - \nSelect and explain. \nA. Infective endocarditis, B. Rheumatic endocarditis, C. Myocardial infarction, D. Tetralogy of Fallot (ToF)", 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]