Incremental backup is a backup method that only backs up the files that have changed since the last backup, whether it was a full or an incremental backup. Incremental backup can save storage space and bandwidth, as it does not copy the same files over and over again. Incremental backup can also retain more versions of backups, as it only stores the changes made to the files. However, incremental backup can have longer restore times, as it requires restoring the last full backup and all the subsequent incremental backups in order to recover the data. The law firm is not concerned about restore times but asks the technician to retain more versions when possible, so incremental backup would be a suitable choice for them.