You Awaken in the Middle of the Night to Find

You awaken in the middle of the night to find your roommate standing in the corner of your room with an aggressive look on his face, punching a pillow, and running in place. Despite this strange behaviour, you realize that your roommate is still asleep, and when you wake him up he shares with you that he was having this bizarre dream about having been involved in a fight while running on a treadmill. Given what you have learned in introductory psychology, it is most likely that your roommate

A) may have narcolepsy
B) was sleepwalking
C) experienced the REM-rebound effect
D) may have REM-sleep behaviour disorder