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: Microbiology
Pneumocystis carinii is diagnosed by - 
Select and explain. 
A. Sputum examination for trophozoites and cyst under microscope, B. Culture, C. Positive serology, D. Growth on artificial media
A: Sputum examination for trophozoites and cyst under microscope
Answer: A: Sputum examination for trophozoites and cyst under microscope 
Explanation: None