You need to ensure that Server1 can send security events to Server2

The network contains two servers named Server1 and Server2 that run Windows Server 2008 R2.

The private cloud contains two servers. The servers are configured as shown in the following table.

The network segments are separated by a firewall. All of the TCP ports from 1 to 1024 are allowed on the firewall.

You need to ensure that Server1 can send security events to Server2.

What should you do?

A.
From the firewall, allow TCP 51909 from Network1 to Network2

B.
From the firewall, allow TCP 5723 from Network1 to Network2

C.
Deploy an Operations Manager gateway server.

D.
Deploy and SMTP smart host.

Explanation:
ACS Forwarders Separated from the ACS Collector by a Firewall

Because of the limited communication between an ACS forwarder and an ACS collector you only need to open the inbound TCP port 51909 on a firewall to enable an ACS forwarder, separated from your network by a firewall, to reach the ACS collector.

http://technet.microsoft.com/en-us/library/bb309575.aspx