You perform differential incremental level 1 backups of your database on each working day and level 0 backup on Sundays， to tape.  Which two statements are true about differential incremental backups（）

• A、The backup performed on Sundays contains all the blocks that have ever been used in the database.
• B、The backup performed on Sundays contains all the blocks that have changed since the last level 1backup. 
• C、The backup performed on each working day contains all the blocks that have changed since the lastlevel 0 backup.
• D、The backup performed on Monday contains all the blocks that have changed since the level 0 backup，and every other working day contains all the blocks that have changed since the level 1 backup.