根据以下材料，回答
Baekeland and Hartmann report that the"short sleepers" had been more or less average in their sleep needsuntil the men were in their teens. But at about age 15 or so, the menvoluntarily began cutting down their nightly sleep time because of pressuresfrom school, work, and other activities. These men tended to view their nightlyperiods of unconsciousness as bothersome interruptions in their daily routines.
In general, these "shortsleepers" appeared ambitious, active, energetic, cheerful, conformist in theiropinions, and very sure about their career choices. They often held severaljobs at once, or worked full-or part-time while going to school. And many ofthem had a strong urge to appear "normal" or "acceptable"to their friends and associates.
When asked to recall their dreams, the"short sleepers" did poorly. More than this, they seemed to prefernot remembering. In similar fashion, their usual way of dealing withpsychological problems was to deny that the problem existed, and then to keepbusy in the hope that the trouble would go away.
The sleep patterns of the "shortsleepers" were similar to, but less extreme than, sleep patterns shown bymany mental patients categorized as manic.
The "long sleepers" were quite different indeed. Baekeland andHartmann report that these young men had been lengthy sleeps since childhood.They seemed to enjoy their sleep, protected it, and were quite concerned whenthey were occasionally deprived of their desired 9 hours of nightly bed rest.They tended to recall their dreams much better than did the "short sleepers."
Many of the "long sleepers" were shy,anxious, introverted, inhibited, passive, mildly depressed, and unsure ofthemselves (particularly in social situations). Several openly state that sleepwas an escape from their daily problems.
According to the report,___________.
A.many short sleepers need less sleep bynature
B.many short sleepers are obliged toreduce their nightly sleep time because they are busy with their work
C.long sleepers sleep a longer period oftime during the day
D.many long sleepers preserve theirsleeping habit formed during their childhood