Your network contains a single Active Directory domain. All domain controllers run Windows Server   2008 R2. There are 1，000 client computers that run Windows 7 and that are connected to managedswitches.   You need to recommend a strategy for network access that meets the following requirements：   èUsers are unable to bypass network access restrictions.   èOnly client computers that have up-to-date service packs installed can access the network.   èOnly client computers that have up-to-date anti-malware software installed can access the network.   What should you recommend？（）

• A、Implement Network Access Protection （NAP） that uses DHCP enforcement.
• B、Implement Network Access Protection （NAP） that uses 802.1x enforcement.
• C、Implement a Network Policy Server （NPS）， and enable IPsec on the domain controllers.
• D、Implement a Network Policy Server （NPS）， and enable Remote Authentication Dial-In User Service  （RADIUS） authentication on the managed switches.