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: Anaesthesia
[{'content': 'All are true regarding nitrous oxide except \nSelect and explain. \nA. Nitrous oxide is good analgesic agent., B. Nitrous oxide cylinder is blue coloured, C. Inhibits thymidylate synthetase enzyme, D. Good agent to use in pan retinal photocoagulation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Nitrous oxide being combustible agent, is contraindicated in laser surgeries.', 'role': 'assistant'}]