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
Which is not a component of  Influenza trivalent vaccine 
Select and explain. 
A. H1N1 virus, B. Influenza B virus, C. H3N2 virus, D. H5N1 virus
D: H5N1 virus
Answer: D: H5N1 virus 
Explanation: It is a trivalent vaccine consisting 
a. H1N1
b. H3N2 
c. Influenza B virus