You are implementing an ASP.NET AJAX page. You add the following control to the page. You need update the contents of the UpdatePanel without causing a full reload of the page. Which two actions should you perform?（）

• A、Add the following control before the UpdatePanel.
• B、Add the following control within the UpdatePanel.
• C、Add an AsyncPostBackTrigger that references Timer1.
• D、Add a PostBackTrigger that references Timer1.