[&] What minimum steps are required to encrypt a managed disk?
- Provision a key vault if necessary. Execute Set-AzVmDiskEncryptionExtension to encrypt the disks on the VM -- Correct
- Execute Set-AzVmEncryptionExtension to encrypt the disks on the VM
- Provision a key vault if necessary. Create a key encrypting key (KEK). Execute Set-AzVmDiskEncryptionExtension to encrypt the disks on the VM
- None.  Azure encrypts VHDs automatically.

[&] Which VM options impact the performance of the OS disk
- VM Size within a series (i.e. D1S_V3 vs. D2S_V3)
- OS disk type -- Correct
- OS disk size -- Correct
- VM Series -- Correct