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
H1N1 strain of influenza is responsible for- 
Select and explain. 
A. Avian influenza, B. Bird flu, C. Swine flu, D. None of the above
C: Swine flu
Answer: C: Swine flu 
Explanation: Ans. is 'c' i.e., Swine flu * Swine flu, also called swine influenza, or pig influenza, is caused by influenza virus.* Incubation period is about 1-3 days and the symptoms of swine flu in humans are similar to most influenza infections, e.g. fever, cough, rhinorrhea, fatigue and headache.* Swine flu is most commonly caused by HJNI inflenza A.* Other influenza virus causing swine flu, occasionally, are H1N2, H2N1, H3N2 and H2N3.