Which of the following represents the correct way to perform an online recovery of datafile 4, which is assigned to a tablespace called USERS?()  
A: shutdown restore datafile 4; recover datafile 4; alter database open;
B: Sql alter database datafile 4 offline; restore datafile 4; recover datafile 4; alter database open;
C: Sql alter database datafile 4 offline; restore datafile 4; Sql alter database datafile 4 online;
D: Sql alter database datafile 4 offline; restore database datafile 4; recover database datafile 4;Sql alter database datafile 4 online;
E: Sql alter database datafile 4 offline; restore datafile 4; recover datafile 4; Sql alter database datafile 4 online;
出自:Oracle认证