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': 'MMR is a - \nSelect and explain. \nA. Rate, B. Ratio, C. Propoion, D. None', 'role': 'user'}, {'content': "Answer: B \nExplanation: Park's textbook of preventive and social medicine 23rd edition. *Maternal moality ratio is defined as (total no of female deaths due to complications of pregnancy,childbih or within 42 days of delivery from puerperal causes in an area during a given year /total no of live bihs in the same area and year)x1000.", 'role': 'assistant'}]