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: Pharmacology
[{'content': 'Which one of the following is not an antiretroviral drug : \nSelect and explain. \nA. Saquinavir, B. Ganciclovir, C. Indinavir, D. Atazanavir', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]