This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable diseases, Subject name: Social & Preventive Medicine
Which of the vaccine strain changed every year 
Select and explain. 
A. Measles, B. Mumps, C. Influenza, D. Polio
C: Influenza
Answer: C: Influenza 
Explanation: Influenza virus under goes antigenic shift and causes epidemics and pandemics. It requires vaccine strain also to be changed regularly Ref:- K Park 24th ed; pg num:- 164