You are managing a 24*7 database. The backup strategy for the database is to perform
user-managed backups.
Identify two prerequisites to perform the backups. (Choose two.)
A.
The database must be opened in restricted mode.
B.
The database must be configured to run in ARCHIVELOG mode.
C.
The tablespaces are required to be in backup mode before taking the backup.
D.
The tablespaces are required to be in read-only mode before taking the backup
B and C are correct:
https://docs.oracle.com/cd/B28359_01/backup.111/b28270/osbackup.htm
For C:
Making User-Managed Backups of Online Read/Write Tablespaces
You must put a read/write tablespace in backup mode to make user-managed datafile backups when the tablespace is online and the database is open. The ALTER TABLESPACE … BEGIN BACKUP statement places a tablespace in backup mode. In backup mode, the database copies whole changed data blocks into the redo stream. After you take the tablespace out of backup mode with the ALTER TABLESPACE … END BACKUP or ALTER DATABASE END BACKUP statement, the database advances the datafile checkpoint SCN to the current database checkpoint SCN.
When restoring a datafile backed up in this way, the database asks for the appropriate set of redo log files to apply if recovery be needed. The redo logs contain all changes required to recover the datafiles and make them consistent.