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': 'Site of lesion in endocarditis of rheumatic heart disease - \nSelect and explain. \nA. Along lines of closure of valves, B. Free margin of valves, C. Both sides of valves, D. Valve cusps', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]