Inthecommunicationchannel,（）thechannelcancommunicatequickly,thecontentofthelettercanbecomplexandsimple,theamountofinformationcanbedetailedandconcise,itcanbesenttospecificpeople,itcanalsobesenttomultiplerecipientsatthesametime.
A.Paperdocuments
B.E-mail
C.Shortmessage
D.Telephone