The correct answer is 'Tape' because this backup type has been traditionally used for archiving data due to its durability and lower cost when dealing with large quantities of data. It is commonly used in offsite storage strategies for disaster recovery purposes. 'Disk' is incorrect as this type of storage is typically used for faster access and is more expensive for large data volumes. 'Snapshot' and 'Incremental' options are used for creating point-in-time copies of data, but it is not typically used for long-term offsite storage.