Mark works as a Software Developer for GenTech Inc. He develops an application, named App1, using Visual Studio .NET. The application contains a Form control, named Form1, which enables users to edit information in a SQL Server database. Mark wants to save all the changes made by users in the database. He defines a boolean variable, named DataIsSaved, in the application code. DataIsSaved indicates whether or not all data are saved in the database. Mark wants to prevent Form1 from closing until all the changes are saved in the database. Which of the following code will he use to accomplish this?