Which file should you add to the project?

You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application.
You want to localize the application to use the German locale settings.
You need to allow the ResourceManager class to retrieve a neutral German locale version of the text to be displayed in the user interface (UI).
Which file should you add to the project?

A.
Resources.de.xml

B.
Resources.de-DE .xml