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)