Meghan is interning as a neurosurgeon in a children's hospital. During one of her hospital visits, a child is brought into the emergency trauma center. A senior doctor asks Meghan to examine the child and note down the child's vital statistics. Meghan notices that the EEG (electroencephalogram) reading has been showing a flat line for a long time. In this scenario, the flat EEG reading is most likely a criterion of .