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