A. By providing the availability required by most applications running in virtual machines, independent of the operating system and application running in it.
B. By using a feature called Changed Block Tracking (CBT), which backs up content.
C. By creating and maintaining a secondary virtual machine that is identical to primary machine.
D. By using the host as the medium to provide asynchronous replication of datastores.
Explanation: VMware Fault Tolerance provides continuous availability for virtual machines by creating and maintaining a Secondary VM that is identical to, and continuously available to replace, the Primary VM in the event of a failover situation. Reference:http://pubs.vmware.com/vsphere-4-esxvcenter/index.jsp?topic=/com.vmware.vsphere.availability.doc_41/c_plan_understand_ft.html