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.