This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Fundamental Concepts, Subject name: Anaesthesia
[{'content': 'Stages of Anaesthesia were established by : \nSelect and explain. \nA. Ether, B. Nitrous Oxide, C. Cyclopropane, D. Chloroform', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' Ether Guedel's staging of Anaesthesia was given for EtherStage of Anaesthesia are as follows*Stage I - Analgesia*Stage II - Delirium or excitement*, partially dilated pupilStage III - Stage of Surgical AnaesthesiaIt is divided in 4 stagesMoving eye to fixed eyeCorneal & laryngeal reflex lostLight reflex lostIntercostal paralysis, Abdominal respiration, Pupils widely dilated*Stage IV - Stage of Medullary Paralysis*", 'role': 'assistant'}]