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': 'What is the sequence which a retrovirus follows on entering a host cell - \nSelect and explain. \nA. RNA-DNA-RNA, B. RNA-DNA, C. DNA-RNA, D. DNA-RNA-DNA', 'role': 'user'}, {'content': 'Answer: A \nExplanation: when virus infect a cell viral RNA is transcribed by enzyme first into ssDNA then to dsDNA REF:MICROBIOLOGY ANANTHA NARAYANAN NINTH EDITION PAGE.571', 'role': 'assistant'}]