You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application that allows users to arrange images. 
You need to ensure that users can arrange child elements in a panel without affecting the size of the elements.  
You also need to ensure that child elements are oriented horizontally. 
Which control should you use?（）

You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. 
You need to ensure that users can view content in a book-reading format that displays two pages at a time. 
Which control should you use?（）