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 interface in the ProductList class.
C. Extend the DependencyObject class in the Product class.
D. Extend the ObservableCollection class in the ProductList class.