One of your databases has archive logging enabled and RMAN backups are taken at regular intervals. The data file for the USERS tablespace is corrupt. Which command must you execute before starting…

`STARTUP FORCE` is used to shut down and restart the entire database instance immediately, which is not the specific command needed to prepare a single tablespace for recovery.

`ALTER TABLESPACE users OFFLINE IMMEDIATE;` takes the tablespace offline without a checkpoint, which is generally not recommended for media recovery as it might require instance recovery if the database crashes before recovery completes.

`SWITCH DATAFILE ALL;` is an RMAN command used to switch a data file to a different copy, typically after restoring a backup or performing a point-in-time recovery, not for taking a tablespace offline for initial preparation.

`ALTER TABLESPACE users OFFLINE NORMAL;` attempts to perform a checkpoint on the tablespace, which can fail or hang if the data files are corrupt, making it unsuitable for initiating recovery of a corrupt tablespace.

When a tablespace's data file is corrupt and requires recovery, the `ALTER TABLESPACE users OFFLINE TEMPORARY;` command must be executed, as it takes the tablespace offline without performing a checkpoint, allowing RMAN to restore data files and apply redo logs for recovery while the database typically remains open.