You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. You add a ListBox control to the application. The ListBox control is data-bound to an instance of a custom collection class of the Product objects named ProductList. You need to ensure that changes to ProductList are automatically reflected in the ListBox control. What should you do? （）

• A、  Implement the INotifyPropertyChanged interface in the Product class.
• B、  Implement the IQueryable<Product> interface in the ProductList class.
• C、  Extend the DependencyObject class in the Product class.
• D、 Extend the ObservableCollection<Product> class in the ProductList class.