A、trAnsport lAyEr protoCol hAs sEvErAl rEsponsiBilitiEs, onE is to CrEAtE A proCEss-to-proCEss (progrAm-to-progrAm) CommuniCAtion; tCp usEs port (11) to ACComplish this.AnothEr rEsponsiBility oF A trAnsport lAyEr protoCol is to CrEAtE A (12) AnD Error-Control mEChAnism At thE trAnsport lEvEl．tCp usEs A sliDing (13) protoCol to AChiEvE Flow Control．it usEs thE ACknowlEDgmEnt pACkEt，timE-out，AnD rEtrAnsmission to AChiEvE (14) Control．thE trAnsport lAyEr is Also rEsponsiBlE For proviDing A ConnECtion mEChAnism For thE AppliCAtion progrAm．thE AppliCAtion progrAm sEnDs (15) oF DAtA to thE trAnsport lAyEr．it is thE rEsponsiBility oF thE trAnsport lAyEr At thE sEnDing stAtion to mAkE A ConnECtion with thE rECEivEr．
A、pACkEt
B．timE
C．Error
D．phAsE