Bart awoke screaming, shaking, and sweating in his heart was beating rapidly. Homer and Marge, being good parents, had Bart hooked up to an EEG. Checking Bart's EEG, they noted that Bart was in stage 4 sleep just before he awoke. From this information, they felt confident in saying that Bart had just experienced __________.
a. a lucid dream
b. an episode of sleep apnea
c. a nightmare
d. sleep terror disorder