Which option activates the creation of a new format incremental backup in tar?

The option that activates the creation of a new format incremental backup in the tar command is indeed represented by the -g flag. When you use the -g option, it allows tar to create an incremental backup based on the snapshot file specified. This snapshot file records the state of the files and directories at the time of the last backup, enabling tar to identify which files have changed since that backup. This is particularly useful in maintaining backups efficiently, as it ensures that only the files that have changed need to be backed up, rather than the entire dataset.

Other options serve different purposes: the -c option is used for creating a new archive, -f specifies the filename of the tar archive being created or extracted, and -t is used to list the contents of an archive. None of these options directly pertain to the process of creating an incremental backup in the manner that the -g option does. Therefore, the -g flag is specifically designed for establishing a new format incremental backup, which is critical for efficient data management and storage practices.