问题：

[单选] Your network contains a server that runs Windows Server 2008. The server has the Network Policy Server （NPS） service role installed. You need to allow only members of a global group named Group1 VPN access to the network. What should you do？（）

A . Add Group1 to the RAS and IAS Servers Group
B . Add Group1 to the Network Configuration Operators group
C . Create a new network policy and define a group-based connection for Group1. Set the access permission of the policy to Access granted. Set the processing order of the policy to 1
D . Create a new network policy and define a group-based condition for Group1. Set the access permission of the policy to Access Granted. Set the processing of the policy to 3.