Which statement is true?

In your multitenant container database (CDB) with two pluggable database (PDBs). You want to
create a new PDB by using SQL Developer.
Which statement is true?

A.
The CDB must be open.

B.
The CDB must be in the mount stage.

C.
The CDB must be in the nomount stage.

D.
Alt existing PDBs must be closed.

Explanation:

* 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.