Final answer:
Electroencephalogram (EEG) is the correct term for brain waves; it records the electrical activity of the brain, showing the frequency and amplitude of brainwaves.
Step-by-step explanation:
The term that refers to brain waves is Electroencephalogram (choice 4). An Electroencephalogram, commonly known as an EEG, is a method used to record the electrical activity of the brain. This technique involves placing an array of electrodes around a person's head to measure the brain's electrical activity with high temporal resolution. The brainwaves recorded show the frequency and amplitude of the brain's electrical activity, which is particularly useful for researchers studying sleep disorders and the various stages and patterns of sleep that occur in both REM and non-REM (NREM) phases. Understanding these patterns can help diagnose and treat various neurological and sleep-related disorders.