What is the correct order of the following commands if you wanted to restore datafile 4， which was accidentally removed from the file system？（） a. sql ’alter database datafile 4 online’ b. restore datafile 4 c. recover datafile 4 d. sql ’alter database datafile 4 offline’ e. startup f. shutdown

A. a， c， b， d
B. d， b， c， a
C. f， d， b， c， a， e
D. c， a， b， d， f
E. a， b， d， e