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
[{'content': 'Shoest incubation period is seen with \nSelect and explain. \nA. Influenza, B. Hepatitis B, C. Hepatitis A, D. Rubella', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Influenza has an incubation period of 18 to 72 hours Incubation period of :- Hepatitis A : 10 to 50 days Hepatitis B : 30 to 180 days Rubella : 2 to 3 weeks Ref : Park&;s Textbook of Preventive and Social Medicine; 23rd edition', 'role': 'assistant'}]