You work as the enterprise exchange administrator at TestKing.com. TestKing.com makes use of Microsoft Exchange Server messaging solution. The TestKing.com network consists of a single ActiveDirectory forest with one domain. The internal network of TestKing.com contains a perimeter network. You have received instructions fromthe CIO to install 15 Edge Transport servers on the perimeter network with the following criteria： * The Edge Transport servers should have a security policy， applied by the administrators. * The minimization of the administrative overhead towards the servers. * The minimization the attack surface of the perimeter network. What should you do？（）

A. The best option is to set up a new Active Directory domain in the internal forest and then join all EdgeTransport servers to the new domain.
B. The best option is to make use of Active Directory Federation Services （AD FS）.
C. The best option is to make use of Network Policy and Access Services （NPAS）.
D. The best option is to set up a new Active Directory domain in the perimeter network and then join all Edge Transport Servers to the new domain.