You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. 
You plan to create a window that has a layout as shown in the following exhibit. 
You need to define the code fragment to create the window layout. You also need to ensure that the window contains a splitter line. 
Which code fragment should you use?（）

You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. 
The application contains a window as shown in the following exhibit. 
You need to define a DockPanel control that fits the window. 
Which code fragment should you use? （）