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
Which of the following statistics should be adjusted for age to allow comparisons 
Select and explain. 
A. Age specific fertility rate, B. Crude mortality rate, C. Perinatal mortality rate, D. Infant mortality rate
B: Crude mortality rate
Answer: B: Crude mortality rate 
Explanation: Crude death rate is adjusted on the basis of age to obtain "Age adjusted or standardized death rates".
Advantage of age adjusted standardized death rates is that it removes all the confounding effects of different age structures and yields a single standardized adjusted rate, by which the mortality experience can be directly compared.