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: Pathology
[{'content': 'In cystic fibrosis the most frequent pulmonary pathogen is \nSelect and explain. \nA. Klebsiella, B. Enterococci, C. Staphylococci, D. Pseudomonas', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Pseudomonas aeruginosa species, in particular, colonize the lower respiratory tract, first intermittently and then chronically.', 'role': 'assistant'}]