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
Vaccine in the UPI which aims at preventing blindness is - 
Select and explain. 
A. Measles, B. Rubella, C. DPT, D. Polio
A: Measles
Answer: A: Measles 
Explanation: Measles blindness is the single leading cause of blindness among children in low-income countries, accounting for an estimated 15,000 to 60,000 cases of blindness per year.