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': 'All circulate in blood except- \nSelect and explain. \nA. HBcAg, B. Anti HBC, C. HBeAg, D. HBsAg', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]