A．sleepwalkers are often awakened by dangersB．the under……

TEXT A
The bizarre antics of sleepwalkers have puzzled police, perplexed scientists, and fascinated writers for centuries. There is an endless supply of stories about sleepwalkers. Person have been said to climb on steep roofs, solve mathematical problems, compose music, walk though plate glass windows, and commit murder in their sleep.
How many of these stories have a basic in fact, and how many are pure fakery No one knows, but if some of the most sensational stories should be taken with a barrel of salt, others are a matter of record.
In Revere, Massachusetts, a hundred policemen combed a waterfront neighborhood for a lost boy who left his home in his sleep and woke up five hours later on a strange sofa in a strange living room, with no idea how he had gone there.
There is an early medical record of a somnambulist who wrote a novel in his sleep. And the great French writer Voltaire knew a sleepwalker who once got our of bed, dressed himself, made a polite bow, danced a minute, and then undressed and went back to bed.
At the university of Iowa, a student was reported to have the habit of getting up in the middle of the night and walking three-quarters of a mile to the Iowa River. He would take a swim and then go back to his room to bed.
The world’ s champion sleepwalker was supposed to have been an Indian, Pandit Ramrakha, who walked sixteen miles along a dangerous road without realizing that he had left his bed. Second in line for the title is probably either a Vienna housewife or a British farmer. The woman did all her shopping on busy streets in her sleep. The farmer, in his sleep, visited a veterinarian miles away.
The leading expert on sleep in American claims that he had never seen a sleepwalker. He is Dr. Nathaniel Kleitman, a physiologist at the University of Chicago. He is said to know more about sleep than any other living man, and during the last thirty-five years had lost a lot of sleep watching people sleep. Says he, "Of course, I know that there are sleepwalkers because I have read about them in the newspapers. But none of my sleepwalkers ever walked, and if I were to advertise for sleepwalkers for an experiment, I doubt that I’ d get many takers."
Sleepwalking, nevertheless, is a scientific reality. Like hypnosis, it is one of those dramatic, eerie, awe -- inspiring phenomena that sometimes border on the fantastic. It lends itself to controversy and misconceptions. What is certain about sleepwalking is that it is a symptom of emotional disturbance, and that the only way to cure it is to remove the worries and anxieties that cause it. Doctors say that somnambulism is much more common than is generally supposed. Some have set estimated that there are four million somnambulists in the United States. Others set the figure even higher. Many sleepwalkers do not seek help and so are never put on record, which means that an accurate count can never be made.
The simplest explanation of sleepwalking is that it is the acting out of vivid dream. The dream usually comes from guilt, worry, nervousness, or some other emotional conflict. The classic sleepwalker is Shakespeare’ s Lady Mac Beth. Her nightly wanderings were caused by her guilty conscience at having committed murder. Shakespeare said of her, "The eyes are open but their sense is shut."
The age-old question is: Is the sleepwalker actually awake or asleep Scientists have decided that he is about half-and-half. Like Lady Mac Beth, he had weighty problems on his mind. Dr. Zelda Teplitz, who made a ten-year study of the subject, say, "Some people stay awake all night worrying about their problems. The sleepwalker thrashes them out in his sleep. He is awake in the muscular area, partially asleep in the sensory area." In other words, a person can walk in his sleep, move around, and do other things, but he does not think about what he is doing.
There are many myths about sleepwalkers. One of the most common is the idea that it’ s dangerous or even fatal to waken a sleepwalker abruptly. Experts say that the shock suffered by a sleepwalker suddenly awakened is no greater than that suffered in waking up to the noise of an alarm clock. Another mistaken belief is that sleepwalkers are immune to injury. Actually most sleepwalkers trip over rugs or hump their heads on doors at some time or other.
What are the chances of a sleepwalker committing a murder or doing something else extraordinary in his sleep Some cases of this have been reported, but they very rarely happen. Of course the few cases that are reported receive a great deal of publicity. Dr. Teplitz say, "Most people have such great inhibitions against murder or violence that they would awaken -- if someone didn’t waken them." In general, authorities on sleepwalking agree with her. They think that people will not do anything in their sleep that is against their own moral code. As for the publicized cases, Dr. Teplitz points out, "Sleepwalking itself is dramatic...sleepwalkers
can always find an audience. I think that some of their tall tales get exaggerated in the telling." In her own file of case histories, there is not one sleepwalker who ever got beyond his own front door.
Parent often explain their children’ s -- or their own -- nocturnal oddities as sleepwalking. Sleepwalking is used as an excuse for all kinds of irrational behavior. There is a ease on record of a woman who dreamed that her house was on fire and flung her baby out of the window. Dr. Teplitz believes that this instance of irrational behavior was not due to somnambulism. She believes the woman was seriously deranged or insane, not a sleepwalker.
For their own protection, chronic sleepwalkers have been known to tie themselves in bed, lock their doors, hide the keys, bolt the windows, and rip up all sorts of gadgets or wake themselves if they should get out of bed. Curiously enough, they have an uncanny way of avoiding their own traps when they sleepwalk, so none of their tricks seem to work very well. Some sleepwalkers talk in their sleep loudly enough to wake someone else in the family who can then shake them back to their senses.
Children who walk in their sleep usually outgrow the habit. In many adults, too, the condition is more or less temporary. If it happens often, however, the sleepwalker should seek help. Although sleepwalking itself is nothing to become alarmed about, the problems that cause the sleepwalking may be very serious.
The writer makes it obvious that ______.

A．sleepwalkers are often awakened by dangers
B．the underlying cause of sleepwalking is more serious than sleepwalking itself
C．most sleepwalkers are deranged or insane
D．all of the above