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 not a structural gene of HIV - \nSelect and explain. \nA. Gag, B. Polio, C. ENV, D. Tat', 'role': 'user'}, {'content': 'Answer: D \nExplanation: tat is a nonstructural and regulatory gene of HIV REF:ANANTHANARAYANAN TEXT BOOK OF MICROBIOLOGY 9EDITION PGNO.572', 'role': 'assistant'}]