Which feature helps maintain zero data loss when a VM on an ESXi server fails unexpectedly?

vMotion is used for live migration of a running VM between hosts without downtime but does not protect against data loss during an unexpected host failure as it's not designed for automatic failover with continuous state synchronization.

VMware Fault Tolerance (FT) provides continuous availability for a virtual machine by creating and maintaining a live shadow instance of that VM on a separate ESXi host. If the primary VM's host experiences an unexpected failure, the shadow VM instantly takes over operations, ensuring zero downtime and, critically, zero data loss because the states of both VMs are kept perfectly synchronized.

Storage vMotion facilitates the live migration of a VM's disk files between datastores without downtime and offers no protection against data loss due to host failure.

vSphere High Availability (HA) automatically restarts VMs on other hosts in the cluster after an ESXi host failure, minimizing downtime, but it can still result in a brief service interruption and potential data loss for in-flight transactions that were not committed at the time of the failure, as the VM is rebooted.