How much additional free space is required on the datastore to delete a snapshot for a powered-off VM with a 100 GB virtual disk and a 20 GB snapshot?

When deleting a snapshot for a powered-off virtual machine (VM), the process involves consolidating the changes recorded in the snapshot back into the base virtual disk. Since the VM is powered off, VMware can directly remove the snapshot without needing to perform any intermediate operations that would require additional disk space.

In this case, the VM has a 100 GB virtual disk and a 20 GB snapshot. When the snapshot is deleted, the data from the snapshot is merged into the base disk, but for a powered-off VM, this operation is efficiently handled without additional space requirements. This is because there aren't any live changes occurring in the VM’s memory; the operation is straightforward, and the storage system allows for the deletion without needing to allocate extra space.

Thus, no additional space is needed on the datastore to delete the snapshot of a powered-off VM, making the correct answer 0 GB.