问题：

[单选]

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.