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