A.Thedirectorymustexistwithonesubdirectory（general）.
B.Thedirectorymustexistwithtwosubdirectories（daily，weekly）.
C.Thedirectorymustexistwiththreesubdirectories（daily，weekly，monthly）.
D.Thedirectorymustexistwithfoursubdirectories（general，daily，weekly，monthly）.