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
A pandemic of H1N1 is suspected when? 
Select and explain. 
A. Cases occur within 2 weeks period, B. Cases are spread over 5 or more cities, C. At least one or more laboratory confirmed H1N1 case, D. 25 or more people are affected
B: Cases are spread over 5 or more cities
Answer: B: Cases are spread over 5 or more cities 
Explanation: Ans. b. Cases are spread over 5 or more cities