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
[{'content': 'Major reason for H5N1 not to become a global pandemic is \nSelect and explain. \nA. Man to man transmission is rare, B. Route of transmission is not respiratory, C. Does not cause serious disease among humans, D. Restricted to few countries only', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Reasons for H5N1 not becoming Global Pandemic\n\nAbsence of efficient human to human mode of transmission (Major reason)\nAbsence of replication in humans\nAbsence of serious disease in humans', 'role': 'assistant'}]