[单项选择] 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