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. Thiopentonc, C. Fentanyl, D. Nitrous oxide', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. 'a' i.e., Ketamine o Ketamine cause emergence reaction which is manifested as hallucinations and illusions.", 'role': 'assistant'}]