You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. The application allows users to post comments to a page that can be viewed by other users. You add a SqlDataSource control named SqlDS. You write the following code segment：   01 private void SaveComment（）   02 {   03   string ipaddr；   04 ►  05   SqlDS1.InsertParameters["IPAddress"].DefaultValue = ipaddr；   06   ...  07   SqlDS1.Insert（）；   08 }   You need to ensure that the IP Address of each user who posts a comment is captured alongwith the user’s comment.  Which code segment should you insert at line 04？（）

• A、ipaddr = Server["REMOTE_ADDR"].ToString(); 
• B、ipaddr = Session["REMOTE_ADDR"].ToString(); 
• C、ipaddr = Application["REMOTE_ADDR"].ToString(); 
• D、ipaddr = Request.ServerVariables["REMOTE_ADDR"].ToString();