This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
[{'content': 'Statistical method of calculate death rate among two population with different age groups- \nSelect and explain. \nA. Crude death rate, B. Standardized death rate, C. Case fatality rate, D. Age specific death rate', 'role': 'user'}, {'content': 'Answer: B \nExplanation: .', 'role': 'assistant'}]