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
WHO vaccination strategy of catch-up, keep-up and follow-up has been designed for 
Select and explain. 
A. Measles, B. Chickenpox, C. Polio, D. Diphtheria
A: Measles
Answer: A: Measles 
Explanation: None