This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: mycology, Subject name: Microbiology
[{'content': 'Pneumocystis carinii is diagnosed by \nSelect and explain. \nA. Sputum examination for trophozoites and cysts under microscope, B. Culture, C. Positive serology, D. Growth on aificial media', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Pneumocystis infection - specimen is induced sputum, bronchoalveolar lavage or lung biopsy. On microscopy - trophozoites can be demonstrated by Giemsa , toludine blue, methenamine silver and calcofluor white stain. Ref: Textbook of Microbiology, Ananthanarayan and Paniker; 9th edition', 'role': 'assistant'}]