Final answer:
The migration option is Live Migration which allows for moving running virtual machines between Hyper-V hosts with minimal downtime and is only available in a failover cluster.
Step-by-step explanation:
The migration option that can be used with Windows Server 2008 Hyper-V servers and is only available between Hyper-V servers in a failover cluster is Live Migration.
Live Migration enables you to move running virtual machines between Hyper-V hosts with minimal downtime. It allows for workload balancing, hardware maintenance, and disaster recovery, ensuring continuous availability.
To perform a Live Migration, the servers must be part of a Failover Cluster, which provides high availability for the virtual machines. This means that the virtual machines need to be stored on a Cluster Shared Volume.