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': 'Hallucinations are seen after ............... anaesthesia : \nSelect and explain. \nA. Ketamine, B. Thiopentone, C. Fentanyl, D. Nitrous oxide', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]