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: Physiology
[{'content': 'Hemophilia B is deficiency of which factor: September 2007 \nSelect and explain. \nA. IX, B. XII, C. VIII, D. X', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A: IX Hemophilia B is also known as Christmas disease. Hemophilia A is deficiency of factor VIII (classical hemophilia).It has sex-linked inheritance.', 'role': 'assistant'}]