You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. You create a Web page that has a GridView control named GridView1. The GridView1 control displays the data from a database named Region and a table named Location. You write the following code segment to populate the GridView1 control：  
01 protected void Page_Load（object sender， EventArgs e）  
02 {  
03   string connstr；  
04  
05   SqlDependency.Start（connstr）；  
06   using （SqlConnection connection =  
07     new SqlConnection（connstr））  
08   {  
09     SqlCommand sqlcmd = new SqlCommand（）；  
10     DateTime expires = DateTime.Now.AddMinutes（30）；  
11     SqlCacheDependency dependency = new  
12       SqlCacheDependency（"Region"， "Location"）； 
13     Response.Cache.SetExpires（expires）；  
14     Response.Cache.SetValidUntilExpires（true）；  
15     Response.AddCacheDependency（dependency）；  
16 ► 
17     sqlcmd.Connection = connection；  
18     GridView1.DataSource = sqlcmd.ExecuteReader（）；  
19     GridView1.DataBind（）；  
20   }  
21 } 
You need to ensure that the proxy servers can cache the content of the GridView1 control. 
Which code segment should you insert at line 16？（）

A.Response.Cache.SetCacheability(HttpCacheability.Private); 
B.Response.Cache.SetCacheability(HttpCacheability.Public); 
C.Response.Cache.SetCacheability(HttpCacheability.Server); 
D.Response.Cache.SetCacheability(HttpCacheability.ServerAndPrivate);