This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Medicine
[{'content': "Vegetations on undersurface of A.V. valves are found in \nSelect and explain. \nA. Acute rheumatic fever, B. Libman Sach's endocarditis, C. Non thrombotic bacterial endocarditis, D. Chronic rheumatic carditis", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref: R Alagappan - Manual of Practical Medicine 4th Edition.pg no:163 Endocarditis associated with SLE (Libman-Sachs endocarditis): The vegetations are 3-4 mm in size, composed of degenerating valve tissue; functional disability is minimal; ventricular surface of the mitral valve is commonly involved; aoic valve involvement is rare; entire valve apparatus can be involved.', 'role': 'assistant'}]