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.