This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Monitoring in Anesthesia, Subject name: Anaesthesia
Depth of anaesthesia can be best assessed by 
Select and explain. 
A. Pulse oximeter, B. End tidal Pco2, C. ABG analysis, D. Bispectral index
D: Bispectral index
Answer: D: Bispectral index 
Explanation: Monitors used to assess depth of anesthesia: Electroencephalography (EEG) Bispectral index (BIS) Entropy Evoked responses (EP) - Motor EP, sensory EP (Auditory, visual, brain stem evoked potential) Patient safety index Narcotrend