Explanation/Reference:
Explanation:
B (not C): You can validate that all database files and archived redo logs can be backed up by running a command as follows:
RMAN> BACKUP VALIDATE DATABASE ARCHIVELOG ALL;
This form of the command would check for physical corruption. To check for logical corruption, RMAN> BACKUP VALIDATE CHECK LOGICAL DATABASE ARCHIVELOG ALL;
D: You can use the VALIDATE keyword of the BACKUP command to do the following:
Check datafiles for physical and logical corruption
Confirm that all database files exist and are in the correct locations.
Note:
You can use the VALIDATE option of the BACKUP command to verify that database files exist and are in the correct locations (D), and have no physical or logical corruptions that would prevent RMAN from creating backups of them. When performing a BACKUP...VALIDATE, RMAN reads the files to be backed up in their entirety, as it would during a real backup. It does not, however, actually produce any backup sets or image copies (Not A, not E).

Note:
* Oracle 12c now provides the ability to index a subset of partitions and to exclude the others.
Local and global indexes can now be created on a subset of the partitions of a table. Partial Global indexes provide
more flexibility in index creation for partitioned tables. For example, index segments can be omitted for the most
recent partitions to ensure maximum data ingest rates without impacting the overall data model and access for the
partitioned object.
Partial Global Indexes save space and improve performance during loads and queries. This feature supports global
indexes that include or index a certain subset of table partitions or subpartitions, and exclude the others. This
operation is supported using a default table indexing property. When a table is created or altered, a default indexing
property can be specified for the table or its partitions.

AC (not E):
The md_restore command allows you to restore a disk group from the metadata created by the
md_backup command.
md_restore can't restore data, only metadata.

* Because temp files cannot be backed up and because no redo is ever generated for them, RMAN never restores or recovers temp files. RMAN does track the names of temp files, but only so that it can automatically re-create them whenneeded.
* If you use RMAN in a Data Guard environment, then RMAN transparently converts primary control files to standby control files and vice versa. RMAN automatically updates file names for data files, online redo logs, standby redo logs, and temp files when you issue
RESTORE and RECOVER.