This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
[{'content': 'The marker for B lymphocyte is \nSelect and explain. \nA. CD19, B. CD68, C. CD34, D. CD4', 'role': 'user'}, {'content': "Answer: A \nExplanation: CD19 is a marker of B lymphocytesPrimarily B cell-associated antigensCD10 and CD19 to CD23 i.e. CD10, CD19, CD20, CD21, CD22, CD23Primarily T cell-associated antigensCD1 to CD8 with the exception of CD6Primarily monocyte macrophage-associated antigensCD13, CD14, CD15, CD33Primarily NK cells associated antigensCD16 and CD56 (also CD2 which is found expressed in a subset(Ref: Harrison's 18/e p2652)", 'role': 'assistant'}]