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': 'Characteristic feature of retrovirus is: \nSelect and explain. \nA. Ribonuclease, B. Reverse transcriptase, C. DNA polymerase, D. Restriction endonuclease', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]