Final answer:
Hailey is likely to spend more time in REM sleep.
Step-by-step explanation:
In the study on dreaming that Hailey is participating in, investigators awaken her every time she dreams to find out what she was dreaming about. Based on this information, tomorrow night Hailey is likely to spend more time in REM sleep (a) as this stage of sleep is associated with dreaming. When individuals are deprived of REM sleep, they tend to experience REM rebound, where they spend more time in REM sleep to make up for the lost REM sleep.