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: Surgery
[{'content': 'Cryoprecipitate is a rich source of - \nSelect and explain. \nA. Thromboplastin, B. Factor VIII, C. Factor X, D. Factor VII', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]