This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology, Subject name: Microbiology
[{'content': 'Hepatitis D virus (delta agent) is a defective virus that can replicate only in cells already infected with which of the following viruses? \nSelect and explain. \nA. Hepatitis A virus, B. Epstein-Barr virus, C. Hepatitis G virus, D. Hepatitis B virus', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Hepatitis D virus is a defective virus with an RNA genome and a hepatitis B surface antigen envelope. Two types of HDV infection occur: simultaneous HDV and HBV infection, or HDV superinfection with chronic HBV infection. Diagnosis is made by demonstrating IgM or IgG antibodies, or both.', 'role': 'assistant'}]