Explanation
Block corruptions can be divided Into Interblock corruption and intrablock corruption. In intrablock corruption. the corruption occurs within the block itself and can be either physical or logical corruption. In interblock corruption, the corruption occurs between blocks and can only be logical corruption.
(key word) * The VALIDATE command checks for intrablock corruptions only. Only DBVERIFY and the ANALYZE statement detect Interblock corruption.
VALIDATE Command Output **> List of Control File and SPFILE.
File TYPE >>> SPFILE or Control File.
Status >>> OK if no corruption, or FAILED If block corruption is found.
Blocks Failing >>> The number of blocks that fail the corruption check. These blocks are newly corrupt.
Blocks Examined >>> Total number of blocks in the file.
Oracle' Database Backup and Recovery User's Guide
12c Release 1 (12.1) - 16 Validating Database Files and Backups

B: Using 12c Resource manager you will be able control CPU, Exadata I/O,
sessions and parallel servers. A new 12c CDB Resource Manager Plan will use so-called "Shares"
(resource allocations) to specify how CPU is distributed between PDBs. A CDB Resource
Manager Plan also can use "utilization limits" to limit the CPU usage for a PDB. With a default
directive, you do not need to modify the resource plan for each PDB plug and unplug.
E: New paradigms for rapid patching and upgrades.
The investment of time and effort to patch one multitenant container database results in patching
all of its many pluggable databases. To patch a single pluggable database, you simply unplug/plug
to a multitenant container database at a different Oracle Database software version.
Incorrect: Not A:
*The Oracle RAC documentation describes special considerations for a CDB in an Oracle RAC environment.
*Oracle Multitenant is a new option for Oracle Database 12c Enterprise Edition that helps
customers reduce IT costs by simplifying consolidation, provisioning, upgrades, and more. It is supported by a new architecture that allows a container database to hold many pluggable databases. And it fully complements other options, including Oracle Real Application Clusters and Oracle Active Data Guard. An existing database can be simply adopted, with no change, as a pluggable database; and no changes are needed in the other tiers of the application. Not D: You can unplug a PDB from one CDB and plug it into a different CDB without altering your schemas or applications. A PDB can be plugged into only one CDB at a time.
not F:
*UNDO tablespace can NOT be local and stays on the CDB level.
*Redo and undo go hand in hand, and so the CDB as a whole has a single undo tablespace per RAC instance.

*Multiprocess and Multithreaded Oracle Database Systems
Multiprocess Oracle Database (also called multiuser Oracle Database) uses several processes to run different parts of the Oracle Database code and additional Oracle processes for the users-- either one process for each connected user or one or more processes shared by multiple users.
Most databases are multiuser because a primary advantage of a database is managing data needed by multiple users simultaneously.
Each process in a database instance performs a specific job. By dividing the work of the database and applications into several processes, multiple users and applications can connect to an instance simultaneously while the system gives good performance.
*In previous releases, Oracle processes did not run as threads on UNIX and Linux systems.
Starting in Oracle Database 12c, the multithreaded Oracle Database model enables Oracle processes to execute as operating system threads in separate address spaces.

Use the CREATE PLUGGABLE DATABASE statement to create a pluggable database (PDB).
This statement enables you to perform the following tasks:
* (A) Create a PDB by using the seed as a template
Use the create_pdb_from_seed clause to create a PDB by using the seed in the multitenant container database (CDB) as a template. The files associated with the seed are copied to a new location and the copied files are then associated with the new PDB.
* (C) Create a PDB by cloning an existing PDB
Use the create_pdb_clone clause to create a PDB by copying an existing PDB (the source PDB) and then plugging the copy into the CDB. The files associated with the source PDB are copied to a new location and the copied files are associated with the new PDB. This operation is called cloning a PDB.
The source PDB can be plugged in or unplugged. If plugged in, then the source PDB can be in the same CDB or in a remote CDB. If the source PDB is in a remote CDB, then a database link is used to connect to the remote CDB and copy the files.
* Create a PDB by plugging an unplugged PDB or a non-CDB into a CDB
Use the create_pdb_from_xml clause to plug an unplugged PDB or a non-CDB into a CDB, using an XML metadata file.