Because of the Effects of Depriving Research Subjects of Either

Because of the effects of depriving research subjects of either REM sleep or stages 3 and 4 NREM deep sleep, it seems clear that:

A) we need to experience the full range of NREM sleep stages and REM sleep.
B) neither REM sleep nor NREM sleep are necessary components of sleep.
C) REM sleep is a necessary component of sleep but deep sleep is not.
D) deep sleep is a necessary component of sleep but REM sleep is not.