What Is a Main Difference Between Sleep Arousal Disorders and Nightmare

What is a main difference between Sleep Arousal Disorders and Nightmare Disorder?

A) Sleep arousal disorders are often associated with other psychological problems, whereas Nightmare Disorder is not.
B) Sleep arousal disorders are often associated with underlying medical problems, whereas Nightmare Disorder is not.
C) Sleep arousal disorders occur during deep sleep, whereas Nightmare Disorder occurs during REM sleep.
D) Older children usually experience sleep arousal disorders, whereas younger children usually experience Nightmare Disorder.