Oracle Database: Backup, Recovery and Performance Tuning

It includes all used data blocks in the datafiles.

It includes a backup of datafiles that includes only the blocks that have changed since a previous incremental backup.

Incremental backups of control files and archived logs always include all blocks in the files.

Incremental backups require a full or incremental level 0 backup to serve as a basis.

Both (2) and (4)