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': 'Which one of the following is a good index of the severity of an acute disease ? \nSelect and explain. \nA. Cause specific death rate, B. Case fatality rate, C. Standardized mortality ratio, D. Five year survival', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Case fatality rate is a proportion and not a rate or ratio.\n\nCase fatality rate (ratio)\n\nCFR represents the killing power (severity) of a disease.\n\nCFR = Total no. of deaths due to disease / Total no. of cases of the same disease x 100', 'role': 'assistant'}]