Ronald wakes up feeling tired and with a headache. his physician suspects he may have sleep apnea, a sleep disorder. to make a proper diagnosis, the doctor uses a(n) to view ronald's brain while he is sleeping.

The doctor uses an EEG or also known as Electroencephalography, this is used to record the activity of the brain, electrically. This will help the doctor make a proper diagnosis of Ronald even if he’s sleeping and to view what type of disorder he has with the given results.

d. groundwater flows through the subsoil and deposits minerals.