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
WHO recommend evaluation of child vaccination in age group? 
Select and explain. 
A. 0-12m, B. 6-12 m, C. 12-23 m, D. 9-12 m
C: 12-23 m
Answer: C: 12-23 m 
Explanation: .in case of mass immunisation programmes implemented by WHO ,including the immunisation programmes ,evaluation of the aaccessibility of such programmes to the populations is usually done among children of age 12 to 23 months. ref:park&;s textbook,22 nd ed,pg 189