What is a characteristic of an EMC Avamar NDMP backup?

Every backup is a level 0 backup.

Level 1 backups are performed daily and merged to a full backup at the end of the week.

Each backup is a level 1 backup, and is merged to a full backup only when a restore request is received.

After the first level 0 backup, level 1 backups are performed and merged to a full backup.