This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Rheumatic Fever, 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: Rheumatic hea disease is one of the forms of vegetative valve disease, each of which exhibit their own characteristic morphologic features. Subendocardial lesions, perhaps excerbated by regurgitant jets, can induce irregular thickening called MacCallum plaques,usually in the left atrium.', 'role': 'assistant'}]