ExaminethefollowingALTERcommand：SQL＞ALTERDISKGROUPdgroup1UNDROPDISKS；Whatisthepurposeofthecommand？（）

A．Itcancelsallpendingdiskdropswithinthediskgroup. B．ItrestoresdisksthatarebeingdroppedastheresultofaDROPDISKGROUPoperation C．Itmountsdisksinthediskgroupforwhichthedrop-diskoperationhasalreadybeencopleted D．Itrestoresallthedroppeddisksinthediskgroupforwhichthedrop-diskoperationhasalreadybeencompleted E．Itaddspreviouslydroppeddisksbackintothediskgroup