Neuroscientists Conducting Research on What Happens in the Brain

Neuroscientists conducting research on what happens in the brain during REM and NREM sleep are likely to find that levels of certain neurotransmitters surge while other neurotransmitters recede. According to Focus on Neuroscience: The Dreaming Brain, which of the following happens during REM sleep?

A) When the activity of REM-on neurons and acetylcholine levels reach a certain threshold, the characteristic signs of REM sleep emerge.
B) When acetylcholine and REM activity peaks, REM-off neuronal activity picks up, increasing serotonin and norepinephrine levels.
C) When REM-off neuronal activity and levels of serotonin and norepinephrine increase to a certain threshold, REM sleep is suppressed and the characteristic features of slow-wave NREM sleep emerge.
D) All of these happen during REM sleep