This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Definition & Concepts, Subject name: Social & Preventive Medicine
[{'content': 'Vital statistics in a population include:- \nSelect and explain. \nA. Sex ratio, B. Age composition, C. Bih rate, D. Dependency ratio', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Population statistics Vital statistics Population size Sex ratio Density of population Dependency ratio Bih rate, death rate Natural growth rate Life expectancy at bih Moality rates Feility rates', 'role': 'assistant'}]