Arlotta has been participating in a study investigating the effects of REM sleep

deprivation. After several nights of being awakened just as she entered each period of
REM sleep, she is allowed to sleep through the entire night.

Electrophysiological
measurements revealed that on this night Arlotta
a. slept about two hours longer than she normally does.
b. slept about two hours longer than she did when she was deprived of REM sleep.
c. spent the typical amount of time in REM sleep.
d. spent more time than normal in REM sleep.
e. spent less time than normal in REM sleep.

d. spent more time than normal in REM sleep.