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: Social & Preventive Medicine
[{'content': 'In a population of 5000, with birth rate of 30/1000 population, 15 children died during first year life in one year: of these 9 died during first month of life. What is the infant mortality rate in this population? \nSelect and explain. \nA. 60, B. 150, C. 45, D. 100', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]