DatafileDF1belongstotablespaceTS1.，andthedatabaseisinARCHIVELOGmode.Youdidanincompleterecoverinthefollowingsteps：1.TakedatafileDF1offline.2.CopyabackupcopyofDF1intothecurrentDF1location.3.ExecuteRECOVERDATAFILEUNTILTIMEsometimeinthepast.4.BringDF1online.5
题目
DatafileDF1belongstotablespaceTS1.，andthedatabaseisinARCHIVELOGmode.Youdidanincompleterecoverinthefollowingsteps：1.TakedatafileDF1offline.2.CopyabackupcopyofDF1intothecurrentDF1location.3.ExecuteRECOVERDATAFILEUNTILTIMEsometimeinthepast.4.BringDF1online.5.ExecuteALTERDATABASEOPENRESETLOGS.Toguaranteethatthedatabaseisrecoverableinthefuture，whatistheleastamountofworkneeded？（）
A.Backupthedatafile.
B.BringtablespaceTS1online.
C.Copyredologstothebackupdirectory.
D.Makeacompletebackuprightafteropeningthedatabase.