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': 'AlI except one are true for hepatitis B \nSelect and explain. \nA. Vertical transmission more important than horizontal, B. Age of onset determines prognosis, C. Period of communicability lasts several months, D. Virus can be found in blood 1 month before jaundice', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]