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
A 40 year old female underwent surgery. Postoperatively she told the anesthetist that she was aware of preoperative events. Individual intraoperative awareness is evaluated by: 
Select and explain. 
A. Cerebral pulse oximetry, B. Colour Doppler, C. Bispectral imaging, D. End tidal CO2
C: Bispectral imaging
Answer: C: Bispectral imaging 
Explanation: C i.e. Bispectral imaging Intraoperative awareness and depth of anaesthesia can be evaluated by BIS (bispectral index)Q