Explanation
* You can include the CONTAINER clause in several SQL statements, such as the CREATE USER, ALTER USER, CREATE ROLE, GRANT, REVOKE, and ALTER SYSTEM statements.
* * CREATE ROLE with CONTAINER (optional) clause
/ CONTAINER = ALL
Creates a common role.
/ CONTAINER = CURRENT
Creates a local role in the current PDB.

* Creating a PDB
Rather than constructing the data dictionary tables that define an empty PDB from scratch, and then populating its
Obj$ and Dependency$ tables, the empty PDB is created when the CDB is created. (Here, we use empty to mean
containing no customer-created artifacts.) It is referred to as the seed PDB and has the name PDB$Seed. Every CDB
non-negotiably contains a seed PDB; it is non-negotiably always open in read-only mode. This has no conceptual
significance; rather, it is just an optimization device. The create PDB operation is implemented as a special case of the
clone PDB operation. The size of the seed PDB is only about 1 gigabyte and it takes only a few seconds on a typical
machine to copy it.

Explanation
B, not A: The PDB must be closed before unplugging it.
D: An unplugged PDB contains data dictionary tables, and some of the columns in these encode information in an endianness-sensitive way. There is no supported way to handle the conversion of such columns automatically. This means, quite simply, that an unplugged PDB cannot be moved across an endianness difference.
E (not F): To exploit the new unplug/plug paradigm for patching the Oracle version most effectively, the source and destination CDBs should share a filesystem so that the PDB's datafiles can remain in place.
References:

Tracing information is present in multiple trace files and you must use the trcsess tool to collect it into a single file.
Incorrect:
Not 1: Parameter service_name
Name of the service forwhich tracing is enabled.
module_name
Name of the MODULE. An optional additional qualifier for the service.
Note:
* The procedure enables a trace for a given combination of Service, MODULE and
ACTION name. The specification is strictly hierarchical: Service Name or Service
Name/MODULE, or Service Name, MODULE, and ACTION name must be specified.
Omitting a qualifier behaves like a wild-card, so that not specifying an ACTION means all
ACTIONs. Using the ALL_ACTIONS constant achieves the same purpose.
* SERV_MOD_ACT_TRACE_ENABLE Procedure
This procedure will enable SQL tracing for a given combination of Service Name, MODULE and ACTION globally unless an instance_name is specified.
* DBMS_MONITOR.SERV_MOD_ACT_TRACE_ENABLE(
service_name IN VARCHAR2,
module_name IN VARCHAR2 DEFAULT ANY_MODULE,
action_name IN VARCHAR2 DEFAULT ANY_ACTION,
waits IN BOOLEAN DEFAULT TRUE,
binds IN BOOLEAN DEFAULT FALSE,
instance_name IN VARCHAR2 DEFAULT NULL);