Which feature guarantees that a virtual machine can power up at another data center in the event of a disaster?

In the context of ensuring a virtual machine can power up at another data center in case of a disaster, the feature that fulfills this requirement is vSphere Replication. This technology provides the ability to replicate virtual machine data to a remote site, thus enabling disaster recovery.

vSphere Replication continuously replicates virtual machine disks and enables recovery by keeping a copy of the VM's data at a secondary location. In the event of a catastrophic failure at the primary site, you can initiate the recovery process at the secondary site, where the replicated data is stored. This allows for a relatively quick restoration of services by powering on the VM using the replicated copies, effectively minimizing downtime.

Other available features like vSphere High Availability and Fault Tolerance focus primarily on ensuring uptime and availability within the same data center environment rather than facilitating the functionality of powering up a VM in a completely different geographic location. vMotion, meanwhile, deals with live migration of VMs between hosts in the same data center without downtime, rather than addressing disaster recovery scenarios. Hence, vSphere Replication is the most suitable solution for ensuring that a VM can be powered up in a different data center during a disaster.