Deprivation of REM Sleep on One Night Results in an Elevated

Deprivation of REM sleep on one night results in an elevated amount of REM sleep on the following night. This rebound phenomenon suggests that

A) emotional well-being requires slow-wave sleep.
B) REM sleep functions to rest the brain.
C) there is a physiological need for stage 1 slow-wave sleep.
D) there is a physiological need for a certain amount of REM sleep.
E) the brain does not regulate REM sleep.