You have two stand-alone servers that run Windows Server 2003 Service Pack 2 （SP2）. You assign the Secure Server （Require security） IPSec policy to both servers. From Server1， you notice that you cannot access resources on Server2. You need to ensure that you can access resources on Server2. All communications between Server1 and Server2 must be encrypted. What should you do？（）

A. On Server1， assign the Client （Respond only） IPSec policy.
B. On Server2， assign the Server （Request Security） IPSec Policy.
C. On Server1 and Server2， modify the authentication settings in the Secure Server （Require security） IPSec Policy.
D. On Server1 and Server2， enable Master Key perfect forward secrecy （PFS） in the Secure Server （Require security） IPSec Policy.