What are two effects of not using the "ENABLE PLUGGABLE database" clause?

You created a new database using the “create database” statement without specifying the
“ENABLE PLUGGABLE” clause.
What are two effects of not using the “ENABLE PLUGGABLE database” clause?

A.
The database is created as a non-CDB and can never contain a PDB.

B.
The database is treated as a PDB and must be plugged into an existing multitenant container
database (CDB).

C.
The database is created as a non-CDB and can never be plugged into a CDB.

D.
The database is created as a non-CDB but can be plugged into an existing CDB.

E.
The database is created as a non-CDB but will become a CDB whenever the first PDB is
plugged in.

Explanation:
A (not B,not E): The CREATE DATABASE … ENABLE PLUGGABLE DATABASE
SQL statement creates a new CDB. If you do not specify the ENABLE PLUGGABLE DATABASE
clause, then the newly created database is a non-CDB and can never contain PDBs.
D: You can create a PDB by plugging in a Non-CDB as a PDB.
The following graphic depicts the options for creating a PDB:

Incorrect:
Not E: For the duration of its existence, a database is either a CDB or a non-CDB. You cannot
transform a non-CDB into a CDB or vice versa. You must define a database as a CDB at creation,
and then create PDBs within this CDB.