Correct Answer :
A. Bedside EEG showing no electrical activity
The definition of brain death is constantly being revised. However, if there is no electrical activity on EEG, and if there is total loss of all brain stem reflexes, then it is safe to label an already irreversibly comatose patient as brain dead. The most definitive measure of absent brain activity is an EEG. However, remember that before interpreting a flat-line EEG, one must ascertain that the patient is not hypothermic or suffering from barbiturate overdose, since these can give the appearance of no electrical activity on an EEG.