You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. You create a Web form in the application by using the following code fragment：  
01 <script runat="server">  
02 protected void Button_Handler（object sender， EventArgs e）  
03 {  
04   // some long-processing operation. 
05 }  
06 </script>  
07 <div>  
08 <asp：ScriptManager ID="defaultScriptManager"  
09   runat="server" />  10 ► 
11 <asp：UpdatePanel ID="defaultPanel"  
12   UpdateMode="Conditional" runat="server"> 
13   <ContentTemplate>  
14   <!-- more content here -->  
15   <asp：Button ID="btnSubmit" runat="server"
16     Text="Submit" OnClick="Button_Handler" />  
17   </ContentTemplate>  
18 </asp：UpdatePanel>  
19 </div>   
You plan to create a client-side script code by using ASP.NET AJAX. 
You need to ensure that while a request is being processed， any subsequent Click events on the btnSubmit Button control are suppressed. 
Which code fragment should you insert at line 10？（）

You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. You write the following code fragment:  
<asp:ScriptManager ID="ScriptManager1" runat="server" />  
<asp:UpdatePanel ID="updateLabels" runat="server" UpdateMode="Conditional">  
<ContentTemplate>  
<asp:Label ID="Label1" runat="server" />  
<asp:Label ID="Label2" runat="server" />  
<asp:Button ID="btnSubmit" runat="server" Text="Submit"   onclick="btnSubmit_Click" />  </ContentTemplate>  
</asp:UpdatePanel>  
<asp:Label id="Label3" runat="server" />   
You need to ensure that when you click the btnSubmit Button control, each Label control value is asynchronously updatable. 
Which code segment should you use?（）