You create a Microsoft ASP.NET application by using the Microsoft .NET Framework version 3.5. You write the following code segment to create a client-script function：   01 function updateLabelControl（labelId， newText） {  02 ► var label = $find（labelId）；  03 ► label.innerHTML = newText；   04 }   The client script function uses ASP.NET AJAX and updates the text of any Label control in the Web form.  When you test the client script function， you discover that the Label controls are not updated. You receive the following JavaScript error message in the browser： "’null’ is null or not an object." You need to resolve the error. What should you do？（）

• A、A
• B、B
• C、C
• D、D