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: Medicine
[{'content': 'Most common cause and the most common valve affected in Infective endocarditis in I.V drug abusers \nSelect and explain. \nA. Streptococcus viridans—tricuspid valve, B. Pseudomonas—mitral valve, C. Staphylococcus aureus—tricuspid valve, D. Streptococcus bovis—mitral valve', 'role': 'user'}, {'content': 'Answer: C \nExplanation: In I.V\xa0drug abusers it is staph.aureus to cause Infective endocarditis most commonly and the right sided valves are more commonly affected than the left sided valves', 'role': 'assistant'}]