You have enabled backup optimization for the RMAN environment. Identify two criteria on which RMAN will skip the file, if it has already been backed up.（） (Choose two.)

• A、The data file backup is done with multiple channels
• B、The data files is in the read-write mode after being backed up in the read only mode
• C、The backup was taken after the data files was taken offline-normal or is in the read only mode
• D、The data file backup complies with the back retention policy and the backup duplexing feature