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
Following can be used as a yardstick for the assessment of standards of therapy ? 
Select and explain. 
A. Specific death rate, B. Case fatality rate, C. Propoional moality rate, D. Survival rate
D: Survival rate
Answer: D: Survival rate 
Explanation: Ans. is `d' i.e., Survival rate Survival rate o It is the propoion of survivors in a group (e.g. of patients) studied and followed over a period of time. o It is a method of describing prognosis in ceain disease conditions. o Survival experience can be used as a yardstick for the assessment of standard of therapy. o Survival rates have received special attention in cancer studies.