If delegated credentials checking has been enabled and remote workers can register to the VCS Expressway, which statement is true?

If delegated credentials checking has been enabled and remote workers can register to the VCS Expressway, which statement is true?
B . 323 message credential checks are delegated.
C . SIP registration proxy mode is set to On in the VCS Expressway.
D . A secure neighbor zone has been configured between the VCS Expressway and the VCS Control.
E . SIP registration proxy mode is set to Off in the VCS Expressway.

Answer: D