Flashback is enabled for your multitenant container database (CDB), which contains two pluggable database (PDBs). A local user was accidently dropped from one of the PDBs. You want to flash back the PDB to the time before the local user was dropped. You connect to the CDB and execute the following commands: SQL > SHUTDOWN IMMEDIATE SQL > STARTUP MOUNT SQL > FLASHBACK DATABASE to TIME “TO_DATE (‘08/20/12’ , ‘MM/DD/YY’)”; Examine following commands: 1. ALTER PLUGGABLE DATABASE ALL OPEN; 2. ALTER DATABASE OPEN; 3. ALTER DATABASE OPEN RESETLOGS; Which command or commands should you execute next to allow updates to the flashback back schema?（）