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: Medicine
All of the following drugs are associated with pure red cell aplasia except 
Select and explain. 
A. Phenytoin, B. Azathioprine, C. Chloramphenicol, D. Ethambutol
D: Ethambutol
Answer: D: Ethambutol 
Explanation: None