How is changed block tracking (CBT) used in a vSphere implementation?

How is changed block tracking (CBT) used in a vSphere implementation?

A.
CBT is used by the VMkernel to reduce time needed for virtual machine copy operations.

B.
CBT is used by VMware Data Protection (VDP) to reduce time needed for backup jobs.

C.
CBT is used by vCenter Server to reduce the size of snapshots.

D.
CBT is used by vSphere Replication for synchronous replication operations.