You need to ensure that when the button is clicked， both update panels update the tim without generating a postback.  What should you do？（）

• A、Add the following marktip to UpdatePanel1.  <Triggers>  <asp:PostBackTrigger ControlID="btnSave" />  </Triggers>  
• B、Set the UpdateMode property for the UpdatePanel2 to "Always"
• C、Add the following markup to UpdatePanel2  <Triggers>  <asp:AsyncPostBackTrigger ControlID="btnSave"  EventName="Click" />  </Triggers>  
• D、Set the UpdateMode property for UpdatePanel2 to "Conditional"