You are the administrator of a Windows XP Professional computer named Pro1.  The computer is connected to the Internet. Pro1 provides Internet access to eight other Windows XP Professional computers that are connected to Pro1. You enable Internet Connection Sharing （ICS） and Internet Connection Firewall （ICF） on Pro1. You run an application named App1 on Pro1.  App1 communicates with an online training company on the Internet. In order to display an online seminar， the training company needs to contact the App1 application at port 5800. You want to ensure that the training company can connect to the App1 application. What should you do?（）

• A、Configure ICF to enable the Internet Control Message Protocol (ICMP) Allow redirect option. Then start the App1 application that opens port 5800.  
• B、Create a new service definition named App1.  Use port 5800 as the external and internal port number. 
• C、Edit the %systemroot%/System32/Drivers/Etc/Services file on Pro1 to include a service definition named App1 for port 5800.  
• D、Change the TCP/IP settings on Pro1 to enable TCP/IP filtering. Permit network traffic on port 5800.