Your company has a single Active Directory domain and an enterprise root certifficate authority. The company plans to use Network Access Protection （NAP） to protect the VPN connections. You build two servers named NPS1 and VPN1. You configure the following functions on the two servers as shown in the following table. You need to ensure that the system health policy is applied to all client computers that attempt VPN connections.What should you do?（）
- A Reconfigure NPS1 as a radius client
- B Reconfigure VPN1 as a radius client
- C Add the NAP role to a domain controller
- D Add the NAP role to an Enterrpise Certificate server.