Anadministratorhasreceivedcomplaintsfromusersthatanapplicationisnotavailablewhileotherapplicationsrun.ThisapplicationresidesonanNFSmountedfilesystem.Whichofthefollowingcommandsshouldberunasareasonablefirststeptohandlethisproblem（）
A.df
B.showmount
C.exportfs
D.refresh-gnfs
正确答案：参考A
