A. The %ROWTYPE attribute declarations in PL/SQL to access a row will not display the invisible column in the output.
B. The DESCRIBE commands in SQL *Plus will not display the invisible column in the output.
C. Referential integrity constraint cannot be set on the invisible column.
D. The invisible column cannot be made visible and can only be marked as unused.
E. A primary key constraint can be added on the invisible column.

A. The PDB must be open in read only mode.
B. The PDB must be dosed.
C. The unplugged PDB becomes a non-cdb.
D. The unplugged PDB can be plugged into the same multitenant container database (CDB)
E. The unplugged PDB can be plugged into another cdb.
F. The PDB data files are automatically removed from disk.