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': 'Which of the following is a defensive virus - \nSelect and explain. \nA. HAV, B. HBV, C. HCV, D. HDV', 'role': 'user'}, {'content': "Answer: D \nExplanation: Screening of blood donors for HBsAg automatically limit bloodborne HDV infection. REF:ANANTHANARAYAN AND PANIKER'S TEXTBOOK OF MICROBIOLOGY 9TH EDITION PAGE NO:550", 'role': 'assistant'}]