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: Pharmacology
Prophylactic therapy should be started against Pneumocystis carinii pneumonia in AIDS patients with CD4 counts below : 
Select and explain. 
A. < 50/microL, B. < 150/ microL, C. < 200/ microL, D. < 400/ microL
C: < 200/ microL
Answer: C: < 200/ microL 
Explanation: None