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
[{'content': 'All of the following are B cell markers except ? \nSelect and explain. \nA. CD 10, B. CD 19, C. CD 20, D. CD 34', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., CD34o CD34 is not a marker of B-cells; it is present on hematopoietic stem cells.", 'role': 'assistant'}]