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
Direct standardization is used to compare the moality rates between two countries. This is done because of the difference in - 
Select and explain. 
A. Cause of death, B. Numerators, C. Age distributions, D. Denominators
C: Age distributions
Answer: C: Age distributions 
Explanation: ref: Park&;s 23rd edition pg 58 A standard population is defined as the one for which the numbers in each age and sex group are known.