单选题

　　[阅读理解]Somewhere around puberty （发育；青春期）， something happens in the timing of the biological clock. （2）The clock pushes forward， so adolescents and teenagers are unable to fall asleep as early as they used to. When your mother tells you it‘s time for bed， your body may be pushing you to stay up for several hours more. And the light coming from your computer screen or TV could be pushing you to stay up even later.

　　What is implied in the second paragraph？

　　A.Young children‘s biological clock has the same rhythm with that of the teenagers.

　　B.People after puberty begin to go to bed earlier due to the change of the biological clock.

　　C.Children before puberty tend to fall asleep earlier at night than adolescents.

　　D.Teenagers go to bed later than they used to due to the light from the computer screen.