You are designing an application by using Windows Presentation Foundation (WPF),
Microsoft .NET Framework 4, and Microsoft SQL Server 2008. The application will contain
several forms that include custom data validators. You need to ensure that data is validated
before the database updates occur. You also need to ensure that the validation logic can be
reused. How should you design the validation?

A.
Implement the INotifyPropertyChanged interface in the data class of the application.

B.
• Subscribe to the MouseLeave event for all user interface (UI) components of the
application. • Perform data validation in the event handler and alert users when a data entry
error occurs.

C.
Implement the IDataErrorlnfo interface in the data class of the application.

D.
• Subscribe to the TextChanged event for all user interface (UI) components of the
application. • Perform data validation in the event handler and alert users when a data entry
error occurs.