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: Social & Preventive Medicine
Shortest incubation period is seen in- 
Select and explain. 
A. Influenza, B. Hepatitis B, C. Hepatitis A, D. Rubella
A: Influenza
Answer: A: Influenza 
Explanation: Mumps → 16 - 18 days
Influenza → 2 - 3 days
Hepatitis A → 15 - 90 days
Hepatitis B →  6 wk to 6 months