This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: parasitology, Subject name: Microbiology
An AIDS patient presented to OPD with dyspnoes and respiratory illness; Which of the following is suitable to diagnose the oppounistic infection commonly seen in AIDS patient 
Select and explain. 
A. Chest Xray, B. CT scan, C. Sputum microscopy, D. Bronchoalveolar lavage
D: Bronchoalveolar lavage
Answer: D: Bronchoalveolar lavage 
Explanation: * Pneumocystis jirovecii pneumonia is more common in AIDS patients. * Fever, unproductive cough, progressive shoness of breath are presenting complaints. Diagnosis is confirmed by: - * Fungal cysts (Toluidine blue) from BAL * Fungal DNA detection by PCR Ref:- Greenwood medical microbiology 18th ed; pg num:- 570