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: Microbiology
[{'content': 'Best epidemiological tool for investigation of hepatitis B is: \nSelect and explain. \nA. Anti-HBsAg, B. Anti-HBcAg, C. Anti-HBeAg, D. HBcAg', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) Anti-HBcAg', 'role': 'assistant'}]