Which disaster recovery option is the LEAST expensive?

Explanations:

Warm standby involves maintaining a partial system, which incurs ongoing costs for infrastructure and management.

Multisite requires maintaining multiple fully functional sites, making it one of the most expensive options due to high redundancy and resource allocation.

Backup and restore is typically the least expensive option as it involves storing backups and restoring them as needed, minimizing ongoing costs.

Pilot light requires keeping minimal resources running, which is more expensive than simple backup and restore due to the maintenance of some operational components.