You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5.  You create an AJAX-enabled Web form by using the following code fragment.  When the updFirstPanel UpdatePanel control is updated， a dynamic client script is registered.  You write the following code segment in the code-behind file of the Web form. （Line numbers are included for reference only.）  01 Protected Sub Page_Load（ByVal sender As Object， _ ByVal e As EventArgs）  02 If Not IsPostBack Then  03 Dim generatedScript As String = _  | English | Chinese | Japan | Korean | - 75 - Test Information Co.， Ltd. All rights reserved. ScriptGenerator.GenerateScript（）  04  05 End If  06 End Sub  You need to ensure that the client-script code is registered only when an asynchronous postback is issued on the updFirstPanel UpdatePanel control.  Which code segment should you insert at line 04？（）

• A、A
• B、B
• C、C
• D、D