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: Microbiology
[{'content': 'A patient has prosthetic valve replacement and he develops endocarditis 8 months later. Organism responsible is - \nSelect and explain. \nA. Staph. aureus, B. Strept. viridans, C. Staph. epidermidis, D. HACEK', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Most common cause of prosthetic valve endocarditis upto 12 months is coagulase-negative staphylococci (staph. epidermidis).', 'role': 'assistant'}]