Explanation
E: You can perform all ALTER PLUGGABLE DATABASE tasks by connecting to a PDB and running the corresponding ALTER DATABASE statement. This functionality is provided to maintain backward compatibility for applications that have been migrated to a CDB environment.
AG: When you issue an ALTER PLUGGABLE DATABASE OPEN statement, READ WRITE is the default unless a PDB being opened belongs to a CDB that is used as a physical standby database, in which case READ ONLY is the default.
You can specify which PDBs to modify in the following ways:
List one or more PDBs.
Specify ALL to modify all of the PDBs.
Specify ALL EXCEPT to modify all of the PDBs, except for the PDBs listed.

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.

Explanation
References: https://docs.oracle.com/cd/B19306_01/server.102/b14231/undo.htm (undo retention)