You use Microsoft Visual Studio 2010 and Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. The application contains a ListBox control named lbxItems that is data-bound to a collection of objects. Each object has a DisplayValue property. You add a Button control to the application. You need to ensure that the Content property of the Button control is data-bound to the DisplayValue property of the selected item of lbxItems. Which binding expression should you use?（）

A. { Binding ElementName=lbxItems, Source=SelectedItem, Path=DisplayValue }
B. { Binding Source=lbxItems, ElementName=SelectedItem, Path=DisplayValue }
C. { Binding ElementName=lbxItems, Path=SelectedItem.DisplayValue }
D. { Binding Source=lbxItems, Path=SelectedItem.DisplayValue }