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: Medicine
[{'content': 'The most severe form of respiratory complication in influenza virus infection is: \nSelect and explain. \nA. Primary viral pneumonia, B. Secondary pseudomonal pneumonia, C. Acute pneumatocele, D. Bilateral pleural effusion', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Primary influenza viral pneumonia is the least common but most severe of the pneumonic complications. The most common bacterial pathogens causing secondary bacterial pneumonia are Streptococcus pneumoniae, Staphylococcus aureus, and Haemophilus influenzae. Ref:Harrisons Principles of Internal Medicine, 18th Edition, Page 1496', 'role': 'assistant'}]