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
Antibiotic prophylaxis is not used for? 
Select and explain. 
A. Child under 15 years, B. In renal failure patient, C. In liver failure patient, D. HIV patient
A: Child under 15 years
Answer: A: Child under 15 years 
Explanation: None