This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pneumonia, Subject name: Medicine
[{'content': 'Which is best for diagnosis of Hypersensitivity pneumonitis? \nSelect and explain. \nA. Chest imaging, B. Pulmonary function testing, C. Serum precipitins, D. Clinical prediction rule', 'role': 'user'}, {'content': "Answer: D \nExplanation: Hypersensitivity pneumonitis: Type IV HSR Chest Imaging - normal in Hypersensitivity pneumonitis Pulmonary function testing - Obstructive pattern Clinical prediction rule- eg Farmer's Lung Exposure to antigen Presence of precipitin Recurrence of symptoms >4-6 hrs Crackles on auscultation Weight loss Farmer lung:- Thermophilus actinomyces", 'role': 'assistant'}]