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': 'Which of the following is the most common method used to know depth of anaesthesia \nSelect and explain. \nA. Oesophageal contractility, B. Depressed Responses, C. Hypotension, D. BIS', 'role': 'user'}, {'content': 'Answer: D \nExplanation: BIS- Bispectral index * BIS monitoring was first introduced for clinical use in 1996. It was approved by FDA as a technique of monitoring depth of anaesthesia and reducing the incidence of intraoperative awareness during General anaesthesia in 2004. * 100 - Awake * 80 - light / moderate sedation * 60 - General anaesthesia * 40 - Deep hypnotic state * 20 - burst suppression * 0 - isoelectric EEG Ref:- Understanding Anesthetic Equipment and Procedures - Baheti & Laheri Pg num:- 304,305', 'role': 'assistant'}]