This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
[{'content': 'True statement about case fatality rate is - \nSelect and explain. \nA. It is ratio, B. It is a propotion, C. Numerator is always constant, D. Numerator and denominator are separate entities', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref: Parks 23rd edition pg 58 it is a propoion. It represents killing power of a disease. It is simply the ratio of deaths to cases.', 'role': 'assistant'}]