which database operation would you need the database to be in the MOUNT state?

For which database operation would you need the database to be in the MOUNT state?

A.
Configuring the database instance to operate in the ARCHIVELOG or NOARCHIVELOG modes

B.
Renaming the control files

C.
Dropping a tablespace in your database

D.
Re-creating the control files

E.
Dropping a user in your database