HOTSPOT
Your network contains an Active Directory domain named contoso.com. The domain
contains a server named Server1 that runs Windows Server 2012 R2.
Server1 has the following BitLocker Drive Encryption (BitLocker) settings:
You need to ensure that drive D will unlock automatically when Server1 restarts. What
command should you run?
To answer, select the appropriate options in the answer area.
Answer: 
Explanation:
Add-BitLockerProtector -MountPoint “D:” -Pin $SecureString -TPMandPinProtector
https://technet.microsoft.com/en-us/library/jj649835.aspx
The URL you reference says “In general, TPM-based protectors can only be associated to an operating system volume.” This is not an Operating System volume, so the AdAccountOrGroupProtector is correct.
Whilst it may be tempting to think that Enable-BitLockerAutoUnlock is the obvious answer. This cmdlet does not support either the third or fourth common parameters provided as options here.
It is the -Service option of Add-BitLockerKeyProtector that Indicates that the system account for this computer unlocks the encrypted volume.
https://technet.microsoft.com/en-us/library/jj649835.aspx
this question was asked in exam
all these questionas could be asked in an exam – thats why they are here 😀
auto unlock is not enabled , if you’re using auto unlock you will need a tpm and password
Add-BitLockerProtector -MountPoint “D: -adaccountorgroup… -service
-service Indicates that the system account for this computer unlocks the encrypted volume.