Slow-Wave Sleep Seems to Play a Particularly Important Role in the Recuperative

Slow-wave sleep seems to play a particularly important role in the recuperative effects of sleep.The following is major evidence for this conclusion:

A) People regain only a small portion of their lost sleep following a period of sleep deprivation, but they regain much of their lost slow-wave sleep.
B) Most long sleepers get a higher proportion of slow-wave sleep than short sleepers.
C) Volunteers who have reduced the amount that they sleep each night have often accomplished this without substantially reducing the amount of slow-wave sleep.
D) all of the above
E) both A and C