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單項(xiàng)選擇題

You use Microsoft .NET Framework 4 to create a Windows Presentation Foundation (WPF) application. 
You add a property named ServiceContext to a control. 
You need the value of ServiceContext to flow to the child controls exactly like the value of the DataContext property of the FrameworkElement class. 
What should you do? ()

A. Inherit the control class from the DependencyObject class.
B. Register a dependency property.   In the options settings of the property metadata, specify the Inherits option.
C. Declare a new property.   In the get and set methods of the new property, create an instance of the TraversalRequest class. 
D. Declare a new property.   In the get method of the new property call VisualTreeHelper.GetParent.   In the set method of the new property, call VisualTreeHelper.GetChild.

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