Extensible Application Markup Language (XAML) is a declarative XML-based language created by Microsoft
XAML is not case sensitive
XAML is used as a user interface markup language to define UI elements, data binding, eventing, and other features
XAML is used extensively in .NET Framework 3.0 technologies, particularly Windows Presentation Foundation, Silverlight, and Windows Workflow Foundation (WF)
XAML is case-sensitive like other XML-based languages, so option B is incorrect. Option A correctly defines XAML as Microsoft's declarative markup language. Option C accurately describes XAML's purpose in defining UI elements and features. Option D correctly lists its use in WPF, Silverlight, and WF.