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
Which of the following is NOT used in treatment of hairy cell leukemia - 
Select and explain. 
A. Steroid, B. Pentostatin, C. Splenectomy, D. alpha-interferon
A: Steroid
Answer: A: Steroid 
Explanation: None