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': 'Haemophilia B is due to mutation of gene corresponding to factor? \nSelect and explain. \nA. Factor 8, B. Factor 9, C. Factor 7, D. Factor 11', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]