A: PGA itself is subdivided. The UGA (User Global Area) contains session state information, including stuff like package-level variables, cursor state, etc. Note that, with shared server, the UGA is in the SGA. It has to be, because shared server means that the session state needs to be accessible to all server processes, as any one of them could be assigned a particular session. However, with dedicated server (which likely what you're using), the UGA is allocated in the PGA.
C: The Location of a private SQL area depends on the type of connection established for a session. If a session is connected through a dedicated server, private SQL areas are located in the server process' PGA.
However, if a session is connected through a shared server, part of the private SQL area is kept in the SGA.
Note:
* System global area (SGA)
The SGA is a group of shared memory structures, known as SGA components, that contain data and control information for one Oracle Database instance. The SGA is shared by all server and background processes.
Examples of data stored in the SGA include cached data blocks and shared SQL areas.
* Program global area (PGA)
A PGA is a memory region that contains data and control information for a server process. It is nonshared memory created by Oracle Database when a server process is started. Access to the PGA is exclusive to the server process. There is one PGA for each server process. Background processes also allocate their own PGAs. The total memory used by all individual PGAs is known as the total instance PGA memory, and the collection of individual PGAs is referred to as the total instance PGA, or just instance PGA. You use database initialization parameters to set the size of the instance PGA, not individual PGAs.

Explanation
A, Not D: In a CDB, PUBLIC is a common role. In a PDB, privileges granted locally to PUBLIC enable all local and common users to exercise these privileges in this PDB only.
C: A user can only perform common operations on a common role, for example, granting privileges commonly to the role, when the following criteria are met:
The user is a common user whose current container is root.
The user has the SET CONTAINER privilege granted commonly, which means that the privilege applies in all containers.
The user has privilege controlling the ability to perform the specified operation, and this privilege has been granted commonly Note:
* Every privilege and role granted to Oracle-supplied users and roles is granted commonly except for system privileges granted to PUBLIC, which are granted locally.

* Oracle Database provides a mechanism to make table structure modifications without significantly affecting the availability of the table. The mechanism is called online table redefinition. Redefining tables online provides a substantial increase in availability compared to traditional methods of redefining tables.
*To redefine a table online:
Choose the redefinition method: by key or by rowid
*By key-Select a primary key or pseudo-primary key to use for the redefinition. Pseudo-primary keys are unique keys with all component columns having NOT NULL constraints. For this method, the versions of the tables before and after redefinition should have the same primary key columns.
This is the preferred and default method of redefinition.
*By rowid-Use this method if no key is available. In this method, a hidden column named M_ROW$$ is added to the post-redefined version of the table. It is recommended that this column be dropped or marked as unused after the redefinition is complete. If COMPATIBLE is set to
10.2.0 or higher, the final phase of redefinition automatically sets this column unused. You can then use the ALTER TABLE ... DROP UNUSED COLUMNS statement to drop it.
You cannot use this method on index-organized tables.
Note:
* When you rebuild an index, you use an existing index as the data source. Creating an index in this manner enables you to change storage characteristics or move to a new tablespace. Rebuilding an index based on an existing data source removes intra-block fragmentation. Compared to dropping the index and using the CREATE INDEX statement, re-creating an existing index offers better performance.
Incorrect:
Not E: Edition-based redefinition enables you to upgrade the database component of an application while it is in use, thereby minimizing or eliminating down time.

Explanation
* To implement your ILM strategy, you can use Heat Map in Oracle Database to track data access and modification.
Heat Map provides data access tracking at the segment-level and data modification tracking at the segment and row level.
* To implement your ILM strategy, you can use Heat Map in Oracle Database to track data access and modification. You can also use Automatic Data Optimization (ADO) to automate the compression and movement of data between different tiers of storage within the database.

*Flashback Database uses its own logging mechanism, creating flashback logs and storing them in the fast recovery area(C). You can only use Flashback Database if flashback logs are available. To take advantage of this feature, you must set up your database in advance to create flashback logs.
*To enable Flashback Database, you configure a fast recovery area and set a flashback retention target. This retention target specifies how far back you can rewind a database with Flashback Database.
From that time onwards, at regular intervals, the database copies images of each altered block in every data file into the flashback logs. These block images can later be reused to reconstruct the data file contents for any moment at which logs were captured.(F)
Incorrect: Not E:You cannot use Flashback Database alone to retrieve a dropped data file. If you flash back a database to a time when a dropped data file existed in the database, only the data file entry is added to the control file. You can only recover the dropped data file by using RMAN to fully restore and recover the data file.
Reference: OracleDatabase Backup and Recovery User's Guide12c R