This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Human Immunodeficiency Virus, Subject name: Microbiology
[{'content': 'Most common oncogenic RNA virus: \nSelect and explain. \nA. Retrovirus, B. Picornavirus, C. Orthomyxovirus, D. Paramyxovirus', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Retrovirus (Ref: Ananthanarayan, 9th/e, p. 565 and 8th/e, p. 563, 565)Retroviruses contain an RNA genome and an RNA-directed DNA polymerase (reverse transcriptase). Both HIV and HTLV are oncogenic retrovirus.", 'role': 'assistant'}]