Which two are true concerning a multitenant container database with three pluggable databases?

PDBs in the same CDB share a single SGA including one buffer cache; they do not each have separate buffer caches - shared memory allocation is a core efficiency benefit of the multitenant architecture, not a per-PDB resource.

PDBs allow many databases to share a single set of Oracle background processes, memory structures, and administrative overhead, dramatically reducing the resources and effort required to consolidate dozens or hundreds of separate databases.

Many DBA tasks such as patching, RMAN backup, and system-level parameter changes are performed once at the CDB root level and apply to all PDBs simultaneously, so administration is not required individually for each PDB.

PDBs decrease patching time compared to equivalent non-CDB databases because a single patch applied to the CDB covers all contained PDBs at once, rather than requiring separate patch application and testing for each standalone database.

All PDBs within a CDB share the same Oracle Database software installation, so a single patch operation on the CDB simultaneously patches all PDBs - reducing patching cycles compared to patching each database individually.