Four-year-old Denise was sound asleep. Suddenly, without warning, she sat straight up and began to scream. Her mother tried to calm her down with no success. Finally, after about 45 seconds of what appeared to be a panic attack, Denise quietly lied back down. When morning came and Denise awoke, she could not remember anything that had happened during the night. It is likely that Denise experienced

• A. somnambulism.
• B. REM rebound.
• C. a nightmare.
• D. a night terror.