You are designing an application by using Windows Presentation Foundation (WPF) and Microsoft .NET Framework 4. The application retrieves customer data from an enterprise resource planning (ERP) system. You need to ensure that the following requirements are met:
* Customer data is retrieved only once.
* Customer data is available on multiple forms within the application.
* Forms can implement TwoWay binding to the customer data.
What should you do?

A.
Store the results of the query in a static DataTable object that is used by all the forms.

B.
Store the results of the query in a local XML file. Bind all forms to an XMLDataAdapter object that references the local XML file.

C.
Design a static class for the data that implements the IObservable interface. Subscribe to the static class from each of the forms that use the data.

D.
Design a static class for the data that implements the INotifyPropertyChanged interface.
Raise the PropertyChanged event to notify the forms when data is changed.