Which data files will be backed up?

Your multitenant container database (CDB) is running in ARCHIVELOG mode. You connect to the CDB RMAN.
Examine the following command and its output:

You execute the following command:
RMAN > BACKUP DATABASE PLUS ARCHIVELOG;
Which data files will be backed up?

A.
Data files that belong to only the root container

B.
Data files that belong to the root container and all the pluggable databases (PDBs)

C.
Data files that belong to only the root container and PDB$SEED

D.
Data files that belong to the root container and all the PDBs excluding PDB$SEED

Explanation:
Backing Up a Whole CDB
Backing up a whole CDB is similar to backing up a non-CDB. When you back up a whole CDB,
RMAN backs up the root, all the PDBs, and the archived redo logs. You can then recover either
the whole CDB, the root only, or one or more PDBs from the CDB backup.
Note:
* You can back up and recover a whole CDB, the root only, or one or more PDBs.
* Backing Up Archived Redo Logs with RMAN
Archived redo logs are the key to successful media recovery. Back them up regularly. You can
back up logs with BACKUP ARCHIVELOG, or back up logs while backing up datafiles and control
files by specifying BACKUP … PLUS ARCHIVELOG.