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': 'Following can be used as a yardstick for the  assessment of standards of therapy - \nSelect and explain. \nA. Specific death rate, B. Case fatality rate, C. Proportional mortality rate, D. Survival rate', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Survival rate \n\nIt is the proportion of survivors in a group (e.g. of patients) studied and followed over a period of time.\nIt is a method of describing prognosis in certain disease conditions.\nSurvival experience can used as a yardstick for the assessment of standard of therapy.\nSurvival rates have received special attention in cancer studies.\n\n5 years of survival rate = Total no. of patients alive after 5 years /\xa0Total no. of patients diagnosed or treated x 100\n\nSurvival period is usually reckoned from the date of diagnosis or start of the treatment.', 'role': 'assistant'}]