You are implementing an ASP.NET page in an e-commerce application. Code in abtnAddToCart_Click event handler adds a product to the shopping cart. The page should check the status of the shopping cart and always show a cart icon when one or more items are in the shopping cart. The page should hide the icon when the shopping cart has no items. You need to add an event handler to implement this requirement. Which event handler should you add？（）

• A、btnAddToCart_Click
• B、Page_Load
• C、Page_PreRender
• D、Page_PreInit