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?（）
- ASet the security layer option to RDP Security Layer.
- BSet the encryption level option to FIPS Compliant.
- CSet the log on option to Always prompt for password.
- DSet the security option to Allow connections only from computers running Remote Desktop with Network Level Authentication.