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?（）

You use Microsoft .NET Framework 4 to create a Windows application.  
You plan to deploy the application by using Trusted Application Deployment. 
The application can only be installed by users who have elevated permissions. 
You need to ensure that users are not prompted for additional permissions when they install the application. 
Which two actions should you perform? （）