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: Microbiology
Antigenic drift is commonly seen in: 
Select and explain. 
A. Influenza B, B. H . influenza, C. Influenza A virus, D. Influenza C
C: Influenza A virus
Answer: C: Influenza A virus 
Explanation: Influenza A virus