This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Anatomy
[{'content': 'Vegetations on under surface of cusps are found in: \nSelect and explain. \nA. Infective endocarditis, B. Libman sacks endocaditis, C. SABE, D. Rheumatic fever', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Vegetations in Libmann sacks endocarditis occur on surfaces of cusps.Both surfaces may be involved but more commonly the undersurface is affected .(ref Robbins 7th/597,89,9/e p558)', 'role': 'assistant'}]