This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology, Subject name: Microbiology
Swine flu is ca used by ? 
Select and explain. 
A. H1N1, B. H5N1, C. H3N1, D. H3N3
A: H1N1
Answer: A: H1N1 
Explanation: Swine infkuenza, a new H1N1 Virus causes swin flue<\p> REF:ANATHANARAYANAN MICROBIOLOGY NINTH EDITION PAGE.503