Which is the correct order of these steps in this case?

Your ARCHIVELOG mode database has lost three datafiles and shut down. One is assigned
to the SYSTEM tablespace and two are assigned to the USERS tablespace. You can
choose from the following steps to recover your database:
a: Restore the three database datafiles that were lost.
b: Issue the Startup Mount command to mount the database.
c: Issue the alter database open command.
d: Issue the alter database open resetlogs command.
e: Recover the database using the recover database command.
f: Recover the datafiles with the recover datafile command.
g: Take the datafiles offline.
Which is the correct order of these steps in this case?

A.
a, b, e, c

B.
b, e, d

C.
a, b, d, c

D.
b, g, c, f

E.
a, b, d, f

Explanation:
Because the system critical data files is damaged, so that the RESETLOGS option is not
applied. four steps to recover the system critical data (SYSTEM tablespace or the
tablespace with UNDO):
1. SHUTDOWN ABORT, if the instance is started.
2. MOUNT the instance
3. restore and recover the damaged data files;
4. OPEN the database