This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Anatomy
[{'content': 'ALL L3 morphology is a malignancy arising from which cell lineage? \nSelect and explain. \nA. Mature B xell, B. Precursor Bcell, C. Immature T cell, D. Mixed B cell and T cell', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Acute lymphoblastic leukemias of the L3 subtype are tumors of Mature B cell ( ref Robbins 7th /677,9th/590)', 'role': 'assistant'}]