This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'Common between B and T cells - \nSelect and explain. \nA. Origin from same cell lineage, B. Site differentiation, C. Antigenic marker, D. Both humoral and cellular immunity', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The key cells in your immune system are lymphocytes known as B cells and T cells, which originate in our bone marrow. After T cells fuher develop in our thymus. Reff: www.mayoclinic.com', 'role': 'assistant'}]