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: Pathology
'Hairy cell leukemia' is a neoplastic proliferation of- 
Select and explain. 
A. T.cells, B. B.cells, C. Myeloid cells, D. Macrophages
B: B.cells
Answer: B: B.cells 
Explanation: None