A. The Oracle database will check all data blocks by going through the data on each block， making sure the data is self-consistent.
B. The DBWn and the direct loader will calculate a checksum and store it in the cache header of every data block when writing it to disk.
C. The Oracle database will check data blocks belonging to the SYSTEM tablespace only， by going through the data on each block， making sure the data is self-consistent.
D. The Oracle database will check data blocks belonging to the SYSAUX tablespace only， by going through the data on each block， making sure the data is self-consistent.
E. The Oracle database will check data blocks in the SYSTEM and SYSAUX tablespaces only， by going through the data on each block， making sure the data is self-consistent.