This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: obstetrics,pediatrics and geriatrics, Subject name: Social & Preventive Medicine
[{'content': 'Child survival index is calculated by? \nSelect and explain. \nA. 1000-IMR\\/10, B. IMR -1000\\/10, C. 1000-U5MR\\/10, D. U5MR-1000\\/10', 'role': 'user'}, {'content': "Answer: C \nExplanation: Park's textbook of preventive and social medicine 23rd edition. *Child survival rate =(1000- under 5 moality rate)/10.", 'role': 'assistant'}]