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: Medicine
[{'content': 'The vaccine currently used against hepatitis B infection is \nSelect and explain. \nA. Killed pooled serum, B. Live attenuated, C. Recombinant, D. Synthetic vaccine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]