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
Shoest incubation period is seen in 
Select and explain. 
A. Hepatitis A, B. Hepatitis B, C. Rubella, D. Influenza
D: Influenza
Answer: D: Influenza 
Explanation: Influenza Causative Agent: Ohomyxovirus, 3 types : A, B, C Type A: MC cause of outbreaks/Epidemics ; Only cause of Pandemics Type B. Type C: Not circulating currently Incubation period : 18-72 hours Period of Infectivity : 1-2 days before to 1-2 days after onset of symptoms Ref:Park's Textbook of Preventive and Social Medicine 25th Edition Pgno : 167-172