多选题Which three statements are true concerning the multitenant architecture?（）AEach pluggable database (PDB) has its own set of background processes.BA PDB can have a private temp tablespace.CPDBs can share the sysaux tablespace.DLog switches occur only at

Each pluggable database (PDB) has its own set of background processes.

A PDB can have a private temp tablespace.

PDBs can share the sysaux tablespace.

Log switches occur only at the multitenant container database (CDB) level.

Different PDBs can have different default block sizes.

PDBs share a common system tablespace.

Instance recovery is always performed at the CDB level.