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A. A filter is added to the table query dynamically using ROWNUM to limit the rows to 20 percent of the total rows
B. All the rows are returned to the client or middle tier but only the first 20 percent are returned to the screen or the application.
C. A view is created during execution and a filter on the view limits the rows to 20 percent of the total rows.
D. A TOP-N query is created to limit the rows to 20 percent of the total rows

A. Backup change tracking will sometimes reduce I/O performed during cumulative incremental backups.
B. The change tracking file must always be backed up when you perform a full database backup.
C. Block change tracking will always reduce I/O performed during cumulative incremental backups.
D. More than one database block may be read by an incremental backup for a change made to a single block.
E. The incremental level 1 backup that immediately follows the enabling of block change tracking will not read the change tracking file to discover changed blocks.