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: Microbiology
[{'content': 'AB blood group antigen are known as....factor ? \nSelect and explain. \nA. Duffy, B. Landsteiner, C. Rhesus, D. Lutheran', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Landsteiner . Human ABO blood group system was discovered by Landsteiner.", 'role': 'assistant'}]