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': 'HLA associated with rheumatoid ahritis is ? \nSelect and explain. \nA. HLA B27, B. HLA DR 4, C. HLABI9, D. HLA DR2', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is `b' i.e. HLA DR4", 'role': 'assistant'}]