Which of the following BEST describes the process of restoring service to a primary datacenter in a controlled manner, following a disaster?

Failover is the process of switching operations to a secondary backup system when the primary site fails, which is the opposite direction of the process described.

Replication is the continuous or scheduled copying of data between systems to maintain synchronization, not a process for restoring service to a datacenter.

Failback specifically describes the deliberate migration of services back to the original primary datacenter following a period of operation at a secondary disaster recovery site. Unlike failover - which is a reactive response to an outage - failback is a planned activity that involves verifying the primary site is healthy before cutting traffic back over. This restores the environment to its intended steady-state architecture after the incident is fully resolved.

Geographical diversity refers to distributing infrastructure across physically separate locations to reduce risk exposure, not a recovery or restoration activity.