Your company has an Active Directory Domain Services (AD DS) domain. All client computers run Windows 7. You have a Remote Desktop Session Host (RD Session Host) server. You need to ensure that each user is authenticated to the RD Session Host server before a session is created. What should you do?（）

A. Set the security layer option to RDP Security Layer.
B. Set the encryption level option to FIPS Compliant.
C. Set the log on option to Always prompt for password.
D. Set the security option to Allow connections only from computers running Remote Desktop with Network Level Authentication.