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': 'Marker of hepatitis infectivity is: \nSelect and explain. \nA. Anti HBc (+), HBsAg (+), B. Anti HBe (+), HBsAg (+), C. Anti HBS (+), HBSAg ( - ), D. HBeAg (- ), HBsAg(-)', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Anti HBc (+), HBsAg (+)', 'role': 'assistant'}]