Final answer:
The correct answer to the question is 'a) Night terror', which is a sleep disturbance where the person experiences intense fear and may scream upon suddenly waking.
Step-by-step explanation:
A night terror is a sleep disturbance characterized by screaming and sudden wakening in a fearful state. Therefore, the correct answer to the question is: a) Night terror. Night terrors result in a sense of panic and are often accompanied by screams. Those experiencing night terrors may appear to be awake, but they commonly have no memory of the events and cannot be consoled during the episode. Generally, this occurs during the NREM phase of sleep. Unlike sleep apnea, which is characterized by pauses in breathing during sleep, or sleepwalking, where an individual might engage in complex behaviors while asleep, night terrors are primarily characterized by intense fear and a state of panic.